Update upstream source from tag 'upstream/3.0.5'

Update to upstream version '3.0.5'
with Debian dir 17ecf804eb411d18bf841acaaf9a2dab2b55f14d

5 files changed, 329 insertions, 192 deletions

diff --git a/script/scons b/script/scons
index fe9d724..c0fe872 100644..100755
--- a/script/scons
+++ b/script/scons
@@ -2,7 +2,7 @@
 #
 # SCons - a Software Constructor
 #
-# Copyright (c) 2001 - 2017 The SCons Foundation
+# Copyright (c) 2001 - 2019 The SCons Foundation
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
@@ -25,22 +25,30 @@
 
 from __future__ import print_function
 
-__revision__ = "src/script/scons.py 74b2c53bc42290e911b334a6b44f187da698a668 2017/11/14 13:16:53 bdbaddog"
+__revision__ = "src/script/scons.py a56bbd8c09fb219ab8a9673330ffcd55279219d0 2019-03-26 23:16:31 bdeegan"
 
-__version__ = "3.0.1"
+__version__ = "3.0.5"
 
-__build__ = "74b2c53bc42290e911b334a6b44f187da698a668"
+__build__ = "a56bbd8c09fb219ab8a9673330ffcd55279219d0"
 
-__buildsys__ = "hpmicrodog"
+__buildsys__ = "kufra"
 
-__date__ = "2017/11/14 13:16:53"
+__date__ = "2019-03-26 23:16:31"
 
-__developer__ = "bdbaddog"
+__developer__ = "bdeegan"
+
+# This is the entry point to the SCons program.
+# The only job of this script is to work out where the guts of the program
+# could be and import them, where the real work begins.
+# SCons can be invoked several different ways
+# - from an installed location
+# - from a "local install" copy
+# - from a source tree, which has a different dir struture than the other two
+# Try to account for all those possibilities.
 
 import os
 import sys
 
-
 ##############################################################################
 # BEGIN STANDARD SCons SCRIPT HEADER
 #
@@ -50,57 +58,53 @@ import sys
 # should also change other scripts that use this same header.
 ##############################################################################
 
-# Strip the script directory from sys.path() so on case-insensitive
-# (WIN32) systems Python doesn't think that the "scons" script is the
-# "SCons" package.  Replace it with our own library directories
-# (version-specific first, in case they installed by hand there,
-# followed by generic) so we pick up the right version of the build
-# engine modules if they're in either directory.
-
-
+# compatibility check
 if (3,0,0) < sys.version_info < (3,5,0) or sys.version_info < (2,7,0):
     msg = "scons: *** SCons version %s does not run under Python version %s.\n\
-Python < 3.5 is not yet supported.\n"
+Python 2.7 or >= 3.5 is required.\n"
     sys.stderr.write(msg % (__version__, sys.version.split()[0]))
     sys.exit(1)
 
-
+# Strip the script directory from sys.path so on case-insensitive
+# (WIN32) systems Python doesn't think that the "scons" script is the
+# "SCons" package.
 script_dir = os.path.dirname(os.path.realpath(__file__))
-
-if script_dir in sys.path:
-    sys.path.remove(script_dir)
+script_path = os.path.realpath(os.path.dirname(__file__))
+if script_path in sys.path:
+    sys.path.remove(script_path)
 
 libs = []
 
 if "SCONS_LIB_DIR" in os.environ:
     libs.append(os.environ["SCONS_LIB_DIR"])
 
-# - running from source takes priority (since 2.3.2), excluding SCONS_LIB_DIR settings
-script_path = os.path.abspath(os.path.dirname(__file__))
-source_path = os.path.join(script_path, '..', 'engine')
-libs.append(source_path)
+# running from source takes 2nd priority (since 2.3.2), following SCONS_LIB_DIR
+source_path = os.path.join(script_path, os.pardir, 'engine')
+if os.path.isdir(source_path):
+    libs.append(source_path)
 
+# add local-install locations
 local_version = 'scons-local-' + __version__
 local = 'scons-local'
 if script_dir:
     local_version = os.path.join(script_dir, local_version)
     local = os.path.join(script_dir, local)
-libs.append(os.path.abspath(local_version))
-libs.append(os.path.abspath(local))
+if os.path.isdir(local_version):
+    libs.append(os.path.abspath(local_version))
+if os.path.isdir(local):
+    libs.append(os.path.abspath(local))
 
 scons_version = 'scons-%s' % __version__
 
 # preferred order of scons lookup paths
 prefs = []
 
-
-# - running from egg check
+# if we can find package information, use it
 try:
     import pkg_resources
 except ImportError:
     pass
 else:
-    # when running from an egg add the egg's directory
     try:
         d = pkg_resources.get_distribution('scons')
     except pkg_resources.DistributionNotFound:
@@ -109,18 +113,18 @@ else:
         prefs.append(d.location)
 
 if sys.platform == 'win32':
-    # sys.prefix is (likely) C:\Python*;
-    # check only C:\Python*.
+    # Use only sys.prefix on Windows
     prefs.append(sys.prefix)
     prefs.append(os.path.join(sys.prefix, 'Lib', 'site-packages'))
 else:
     # On other (POSIX) platforms, things are more complicated due to
-    # the variety of path names and library locations.  Try to be smart
-    # about it.
+    # the variety of path names and library locations.
+    # Build up some possibilities, then transform them into candidates
+    temp = []
     if script_dir == 'bin':
         # script_dir is `pwd`/bin;
         # check `pwd`/lib/scons*.
-        prefs.append(os.getcwd())
+        temp.append(os.getcwd())
     else:
         if script_dir == '.' or script_dir == '':
             script_dir = os.getcwd()
@@ -128,42 +132,41 @@ else:
         if tail == "bin":
             # script_dir is /foo/bin;
             # check /foo/lib/scons*.
-            prefs.append(head)
+            temp.append(head)
 
     head, tail = os.path.split(sys.prefix)
     if tail == "usr":
         # sys.prefix is /foo/usr;
         # check /foo/usr/lib/scons* first,
         # then /foo/usr/local/lib/scons*.
-        prefs.append(sys.prefix)
-        prefs.append(os.path.join(sys.prefix, "local"))
+        temp.append(sys.prefix)
+        temp.append(os.path.join(sys.prefix, "local"))
     elif tail == "local":
         h, t = os.path.split(head)
         if t == "usr":
             # sys.prefix is /foo/usr/local;
             # check /foo/usr/local/lib/scons* first,
             # then /foo/usr/lib/scons*.
-            prefs.append(sys.prefix)
-            prefs.append(head)
+            temp.append(sys.prefix)
+            temp.append(head)
         else:
             # sys.prefix is /foo/local;
             # check only /foo/local/lib/scons*.
-            prefs.append(sys.prefix)
+            temp.append(sys.prefix)
     else:
         # sys.prefix is /foo (ends in neither /usr or /local);
         # check only /foo/lib/scons*.
-        prefs.append(sys.prefix)
+        temp.append(sys.prefix)
+
+    # suffix these to add to our original prefs:
+    prefs.extend([os.path.join(x, 'lib') for x in temp])
+    prefs.extend([os.path.join(x, 'lib', 'python' + sys.version[:3],
+                               'site-packages') for x in temp])
 
-    temp = [os.path.join(x, 'lib') for x in prefs]
-    temp.extend([os.path.join(x,
-                                           'lib',
-                                           'python' + sys.version[:3],
-                                           'site-packages') for x in prefs])
-    prefs = temp
 
     # Add the parent directory of the current python's library to the
-    # preferences.  On SuSE-91/AMD64, for example, this is /usr/lib64,
-    # not /usr/lib.
+    # preferences.  This picks up differences between, e.g., lib and lib64,
+    # and finds the base location in case of a non-copying virtualenv.
     try:
         libpath = os.__file__
     except AttributeError:
@@ -177,9 +180,9 @@ else:
         prefs.append(libpath)
 
 # Look first for 'scons-__version__' in all of our preference libs,
-# then for 'scons'.
-libs.extend([os.path.join(x, scons_version) for x in prefs])
-libs.extend([os.path.join(x, 'scons') for x in prefs])
+# then for 'scons'.  Skip paths that do not exist.
+libs.extend([os.path.join(x, scons_version) for x in prefs if os.path.isdir(x)])
+libs.extend([os.path.join(x, 'scons') for x in prefs if os.path.isdir(x)])
 
 sys.path = libs + sys.path
 
@@ -191,9 +194,9 @@ if __name__ == "__main__":
     try:
         import SCons.Script
     except ImportError:
-        print("SCons import failed. Unable to find engine files in:")
+        sys.stderr.write("SCons import failed. Unable to find engine files in:\n")
         for path in libs:
-            print("  {}".format(path))
+            sys.stderr.write("  {}\n".format(path))
         raise
 
     # this does all the work, and calls sys.exit
diff --git a/script/scons-configure-cache b/script/scons-configure-cache
index cbb058d..798b8fa 100644
--- a/script/scons-configure-cache
+++ b/script/scons-configure-cache
@@ -2,7 +2,7 @@
 #
 # SCons - a Software Constructor
 #
-# Copyright (c) 2001 - 2017 The SCons Foundation
+# Copyright (c) 2001 - 2019 The SCons Foundation
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
@@ -23,102 +23,139 @@
 # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+'''Show or convert the configuration of an SCons cache directory.
+
+A cache of derived files is stored by file signature.
+The files are split into directories named by the first few
+digits of the signature. The prefix length used for directory
+names can be changed by this script.
+'''
+
 from __future__ import print_function
+import argparse
+import glob
+import json
+import os
 
-__revision__ = "src/script/scons-configure-cache.py 74b2c53bc42290e911b334a6b44f187da698a668 2017/11/14 13:16:53 bdbaddog"
+__revision__ = "src/script/scons-configure-cache.py a56bbd8c09fb219ab8a9673330ffcd55279219d0 2019-03-26 23:16:31 bdeegan"
 
-__version__ = "3.0.1"
+__version__ = "3.0.5"
 
-__build__ = "74b2c53bc42290e911b334a6b44f187da698a668"
+__build__ = "a56bbd8c09fb219ab8a9673330ffcd55279219d0"
 
-__buildsys__ = "hpmicrodog"
+__buildsys__ = "kufra"
 
-__date__ = "2017/11/14 13:16:53"
+__date__ = "2019-03-26 23:16:31"
 
-__developer__ = "bdbaddog"
+__developer__ = "bdeegan"
 
-import argparse
-import glob
-import json
-import os
 
 def rearrange_cache_entries(current_prefix_len, new_prefix_len):
-    print('Changing prefix length from', current_prefix_len, 'to', new_prefix_len)
+    '''Move cache files if prefix length changed.
+
+    Move the existing cache files to new directories of the
+    appropriate name length and clean up the old directories.
+    '''
+    print('Changing prefix length from', current_prefix_len,
+          'to', new_prefix_len)
     dirs = set()
     old_dirs = set()
     for file in glob.iglob(os.path.join('*', '*')):
         name = os.path.basename(file)
-        dir = name[:current_prefix_len].upper()
-        if dir not in old_dirs:
-            print('Migrating', dir)
-            old_dirs.add(dir)
-        dir = name[:new_prefix_len].upper()
-        if dir not in dirs:
-            os.mkdir(dir)
-            dirs.add(dir)
-        os.rename(file, os.path.join(dir, name))
+        dname = name[:current_prefix_len].upper()
+        if dname not in old_dirs:
+            print('Migrating', dname)
+            old_dirs.add(dname)
+        dname = name[:new_prefix_len].upper()
+        if dname not in dirs:
+            os.mkdir(dname)
+            dirs.add(dname)
+        os.rename(file, os.path.join(dname, name))
 
     # Now delete the original directories
-    for dir in old_dirs:
-        os.rmdir(dir)
+    for dname in old_dirs:
+        os.rmdir(dname)
+
 
-# This dictionary should have one entry per entry in the cache config
-# Each entry should have the following:
+# The configuration dictionary should have one entry per entry in the
+# cache config. The value of each entry should include the following:
 #   implicit - (optional) This is to allow adding a new config entry and also
 #              changing the behaviour of the system at the same time. This
-#              indicates the value the config entry would have had if it had been
-#              specified.
+#              indicates the value the config entry would have had if it had
+#              been specified.
 #   default - The value the config entry should have if it wasn't previously
 #             specified
 #   command-line - parameters to pass to ArgumentParser.add_argument
-#   converter - (optional) Function to call if it's necessary to do some work
+#   converter - (optional) Function to call if conversion is required
 #               if this configuration entry changes
 config_entries = {
-    'prefix_len' : { 
-        'implicit' : 1, 
-        'default' : 2 ,
-        'command-line' : {
-            'help' : 'Length of cache file name used as subdirectory prefix',
-            'metavar' : '<number>',
-            'type' : int
-            },
-        'converter' : rearrange_cache_entries
+    'prefix_len': {
+        'implicit': 1,
+        'default': 2,
+        'command-line': {
+            'help': 'Length of cache file name used as subdirectory prefix',
+            'metavar': '<number>',
+            'type': int
+        },
+        'converter': rearrange_cache_entries
     }
 }
+
 parser = argparse.ArgumentParser(
-    description = 'Modify the configuration of an scons cache directory',
-    epilog = '''
-             Unless you specify an option, it will not be changed (if it is
-             already set in the cache config), or changed to an appropriate
-             default (it it is not set).
-             '''
-    )
+    description='Modify the configuration of an scons cache directory',
+    epilog='''
+           Unspecified options will not be changed unless they are not
+           set at all, in which case they are set to an appropriate default.
+           ''')
 
 parser.add_argument('cache-dir', help='Path to scons cache directory')
 for param in config_entries:
-    parser.add_argument('--' + param.replace('_', '-'), 
+    parser.add_argument('--' + param.replace('_', '-'),
                         **config_entries[param]['command-line'])
-parser.add_argument('--version', action='version', version='%(prog)s 1.0')
+parser.add_argument('--version',
+                    action='version',
+                    version='%(prog)s 1.0')
+parser.add_argument('--show',
+                    action="store_true",
+                    help="show current configuration")
 
 # Get the command line as a dict without any of the unspecified entries.
 args = dict([x for x in vars(parser.parse_args()).items() if x[1]])
 
 # It seems somewhat strange to me, but positional arguments don't get the -
 # in the name changed to _, whereas optional arguments do...
-os.chdir(args['cache-dir'])
+cache = args['cache-dir']
+if not os.path.isdir(cache):
+    raise RuntimeError("There is no cache directory named %s" % cache)
+os.chdir(cache)
 del args['cache-dir']
 
 if not os.path.exists('config'):
+    # old config dirs did not have a 'config' file. Try to update.
     # Validate the only files in the directory are directories 0-9, a-f
-    expected = [ '{:X}'.format(x) for x in range(0, 16) ]
+    expected = ['{:X}'.format(x) for x in range(0, 16)]
     if not set(os.listdir('.')).issubset(expected):
-        raise RuntimeError("This doesn't look like a version 1 cache directory")
+        raise RuntimeError(
+            "%s does not look like a valid version 1 cache directory" % cache)
     config = dict()
 else:
     with open('config') as conf:
         config = json.load(conf)
 
-# Find any keys that aren't currently set but should be
+if args.get('show', None):
+    print("Current configuration in '%s':" % cache)
+    print(json.dumps(config, sort_keys=True,
+                     indent=4, separators=(',', ': ')))
+    # in case of the show argument, emit some stats as well
+    file_count = 0
+    for _, _, files in os.walk('.'):
+        file_count += len(files)
+    if file_count:  # skip config file if it exists
+        file_count -= 1
+    print("Cache contains %s files" % file_count)
+    del args['show']
+
+# Find any keys that are not currently set but should be
 for key in config_entries:
     if key not in config:
         if 'implicit' in config_entries[key]:
@@ -128,10 +165,10 @@ for key in config_entries:
         if key not in args:
             args[key] = config_entries[key]['default']
 
-#Now we go through each entry in args to see if it changes an existing config
-#setting.
+# Now go through each entry in args to see if it changes an existing config
+# setting.
 for key in args:
-    if args[key] != config[key]:        
+    if args[key] != config[key]:
         if 'converter' in config_entries[key]:
             config_entries[key]['converter'](config[key], args[key])
         config[key] = args[key]
diff --git a/script/scons-time b/script/scons-time
index 3fdb8f2..26ddd77 100644
--- a/script/scons-time
+++ b/script/scons-time
@@ -9,7 +9,7 @@
 #
 
 #
-# Copyright (c) 2001 - 2017 The SCons Foundation
+# Copyright (c) 2001 - 2019 The SCons Foundation
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
@@ -31,7 +31,7 @@
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 from __future__ import division, print_function
 
-__revision__ = "src/script/scons-time.py 74b2c53bc42290e911b334a6b44f187da698a668 2017/11/14 13:16:53 bdbaddog"
+__revision__ = "src/script/scons-time.py a56bbd8c09fb219ab8a9673330ffcd55279219d0 2019-03-26 23:16:31 bdeegan"
 
 import getopt
 import glob
@@ -58,12 +58,12 @@ def make_temp_file(**kw):
     return result
 
 def HACK_for_exec(cmd, *args):
-    '''
+    """
     For some reason, Python won't allow an exec() within a function
     that also declares an internal function (including lambda functions).
     This function is a hack that calls exec() in a function with no
     internal functions.
-    '''
+    """
     if not args:          exec(cmd)
     elif len(args) == 1:  exec(cmd, args[0])
     else:                 exec(cmd, args[0], args[1])
@@ -147,7 +147,7 @@ class Gnuplotter(Plotter):
         return line.plot_string()
 
     def vertical_bar(self, x, type, label, comment):
-        if self.get_min_x() <= x and x <= self.get_max_x():
+        if self.get_min_x() <= x <= self.get_max_x():
             points = [(x, 0), (x, self.max_graph_value(self.get_max_y()))]
             self.line(points, type, label, comment)
 
@@ -814,7 +814,9 @@ class SConsTimer(object):
                 self.title = a
 
         if self.config_file:
-            exec(open(self.config_file, 'r').read(), self.__dict__)
+            with open(self.config_file, 'r') as f:
+                config = f.read()
+            exec(config, self.__dict__)
 
         if self.chdir:
             os.chdir(self.chdir)
@@ -933,7 +935,9 @@ class SConsTimer(object):
                 self.title = a
 
         if self.config_file:
-            HACK_for_exec(open(self.config_file, 'r').read(), self.__dict__)
+            with open(self.config_file, 'r') as f:
+                config = f.read()
+            HACK_for_exec(config, self.__dict__)
 
         if self.chdir:
             os.chdir(self.chdir)
@@ -1053,7 +1057,9 @@ class SConsTimer(object):
         object_name = args.pop(0)
 
         if self.config_file:
-            HACK_for_exec(open(self.config_file, 'r').read(), self.__dict__)
+            with open(self.config_file, 'r') as f:
+                config = f.read()
+            HACK_for_exec(config, self.__dict__)
 
         if self.chdir:
             os.chdir(self.chdir)
@@ -1191,7 +1197,9 @@ class SConsTimer(object):
             sys.exit(1)
 
         if self.config_file:
-            exec(open(self.config_file, 'r').read(), self.__dict__)
+            with open(self.config_file, 'r') as f:
+                config = f.read()
+            exec(config, self.__dict__)
 
         if args:
             self.archive_list = args
diff --git a/script/scons.bat b/script/scons.bat
index 4d0e6e6..45c77ab 100644
--- a/script/scons.bat
+++ b/script/scons.bat
@@ -1,11 +1,11 @@
-@REM Copyright (c) 2001 - 2017 The SCons Foundation

-@REM src/script/scons.bat 74b2c53bc42290e911b334a6b44f187da698a668 2017/11/14 13:16:53 bdbaddog

+@REM Copyright (c) 2001 - 2019 The SCons Foundation

+@REM src/script/scons.bat a56bbd8c09fb219ab8a9673330ffcd55279219d0 2019-03-26 23:16:31 bdeegan

 @echo off

 set SCONS_ERRORLEVEL=

 if "%OS%" == "Windows_NT" goto WinNT

 

 @REM for 9x/Me you better not have more than 9 args

-python -c "from os.path import join; import sys; sys.path = [ join(sys.prefix, 'Lib', 'site-packages', 'scons-3.0.1'), join(sys.prefix, 'Lib', 'site-packages', 'scons'), join(sys.prefix, 'scons-3.0.1'), join(sys.prefix, 'scons')] + sys.path; import SCons.Script; SCons.Script.main()" %1 %2 %3 %4 %5 %6 %7 %8 %9

+python -c "from os.path import join; import sys; sys.path = [ join(sys.prefix, 'Lib', 'site-packages', 'scons-3.0.5'), join(sys.prefix, 'Lib', 'site-packages', 'scons'), join(sys.prefix, 'scons-3.0.5'), join(sys.prefix, 'scons')] + sys.path; import SCons.Script; SCons.Script.main()" %1 %2 %3 %4 %5 %6 %7 %8 %9

 @REM no way to set exit status of this script for 9x/Me

 goto endscons

 

@@ -16,10 +16,14 @@ goto endscons
 :WinNT

 setlocal

 @REM ensure the script will be executed with the Python it was installed for

-set path=%~dp0;%~dp0..;%path%

+pushd %~dp0..

+set path=%~dp0;%CD%;%path%

+popd

 @REM try the script named as the .bat file in current dir, then in Scripts subdir

 set scriptname=%~dp0%~n0.py

 if not exist "%scriptname%" set scriptname=%~dp0Scripts\%~n0.py

+@REM Handle when running from wheel where the script has no .py extension

+if not exist "%scriptname%" set scriptname=%~dp0%~n0

 python "%scriptname%" %*

 endlocal & set SCONS_ERRORLEVEL=%ERRORLEVEL%

 

diff --git a/script/sconsign b/script/sconsign
index 7391807..3b1e52d 100644
--- a/script/sconsign
+++ b/script/sconsign
@@ -2,7 +2,7 @@
 #
 # SCons - a Software Constructor
 #
-# Copyright (c) 2001 - 2017 The SCons Foundation
+# Copyright (c) 2001 - 2019 The SCons Foundation
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
@@ -25,17 +25,17 @@
 
 from __future__ import print_function
 
-__revision__ = "src/script/sconsign.py 74b2c53bc42290e911b334a6b44f187da698a668 2017/11/14 13:16:53 bdbaddog"
+__revision__ = "src/script/sconsign.py a56bbd8c09fb219ab8a9673330ffcd55279219d0 2019-03-26 23:16:31 bdeegan"
 
-__version__ = "3.0.1"
+__version__ = "3.0.5"
 
-__build__ = "74b2c53bc42290e911b334a6b44f187da698a668"
+__build__ = "a56bbd8c09fb219ab8a9673330ffcd55279219d0"
 
-__buildsys__ = "hpmicrodog"
+__buildsys__ = "kufra"
 
-__date__ = "2017/11/14 13:16:53"
+__date__ = "2019-03-26 23:16:31"
 
-__developer__ = "bdbaddog"
+__developer__ = "bdeegan"
 
 import os
 import sys
@@ -49,48 +49,53 @@ import sys
 # should also change other scripts that use this same header.
 ##############################################################################
 
-# Strip the script directory from sys.path() so on case-insensitive
-# (WIN32) systems Python doesn't think that the "scons" script is the
-# "SCons" package.  Replace it with our own library directories
-# (version-specific first, in case they installed by hand there,
-# followed by generic) so we pick up the right version of the build
-# engine modules if they're in either directory.
-
+# compatibility check
+if (3,0,0) < sys.version_info < (3,5,0) or sys.version_info < (2,7,0):
+    msg = "scons: *** SCons version %s does not run under Python version %s.\n\
+Python 2.7 or >= 3.5 is required.\n"
+    sys.stderr.write(msg % (__version__, sys.version.split()[0]))
+    sys.exit(1)
 
+# Strip the script directory from sys.path so on case-insensitive
+# (WIN32) systems Python doesn't think that the "scons" script is the
+# "SCons" package.
 script_dir = os.path.dirname(os.path.realpath(__file__))
-
-if script_dir in sys.path:
-    sys.path.remove(script_dir)
+script_path = os.path.realpath(os.path.dirname(__file__))
+if script_path in sys.path:
+    sys.path.remove(script_path)
 
 libs = []
 
 if "SCONS_LIB_DIR" in os.environ:
     libs.append(os.environ["SCONS_LIB_DIR"])
 
-# - running from source takes priority (since 2.3.2), excluding SCONS_LIB_DIR settings
-script_path = os.path.abspath(os.path.dirname(__file__))
-source_path = os.path.join(script_path, '..', 'engine')
-libs.append(source_path)
+# running from source takes 2nd priority (since 2.3.2), following SCONS_LIB_DIR
+source_path = os.path.join(script_path, os.pardir, 'engine')
+if os.path.isdir(source_path):
+    libs.append(source_path)
 
+# add local-install locations
 local_version = 'scons-local-' + __version__
 local = 'scons-local'
 if script_dir:
     local_version = os.path.join(script_dir, local_version)
     local = os.path.join(script_dir, local)
-libs.append(os.path.abspath(local_version))
-libs.append(os.path.abspath(local))
+if os.path.isdir(local_version):
+    libs.append(os.path.abspath(local_version))
+if os.path.isdir(local):
+    libs.append(os.path.abspath(local))
 
 scons_version = 'scons-%s' % __version__
 
 # preferred order of scons lookup paths
 prefs = []
 
+# if we can find package information, use it
 try:
     import pkg_resources
 except ImportError:
     pass
 else:
-    # when running from an egg add the egg's directory
     try:
         d = pkg_resources.get_distribution('scons')
     except pkg_resources.DistributionNotFound:
@@ -99,18 +104,18 @@ else:
         prefs.append(d.location)
 
 if sys.platform == 'win32':
-    # sys.prefix is (likely) C:\Python*;
-    # check only C:\Python*.
+    # Use only sys.prefix on Windows
     prefs.append(sys.prefix)
     prefs.append(os.path.join(sys.prefix, 'Lib', 'site-packages'))
 else:
     # On other (POSIX) platforms, things are more complicated due to
-    # the variety of path names and library locations.  Try to be smart
-    # about it.
+    # the variety of path names and library locations.
+    # Build up some possibilities, then transform them into candidates
+    temp = []
     if script_dir == 'bin':
         # script_dir is `pwd`/bin;
         # check `pwd`/lib/scons*.
-        prefs.append(os.getcwd())
+        temp.append(os.getcwd())
     else:
         if script_dir == '.' or script_dir == '':
             script_dir = os.getcwd()
@@ -118,58 +123,57 @@ else:
         if tail == "bin":
             # script_dir is /foo/bin;
             # check /foo/lib/scons*.
-            prefs.append(head)
+            temp.append(head)
 
     head, tail = os.path.split(sys.prefix)
     if tail == "usr":
         # sys.prefix is /foo/usr;
         # check /foo/usr/lib/scons* first,
         # then /foo/usr/local/lib/scons*.
-        prefs.append(sys.prefix)
-        prefs.append(os.path.join(sys.prefix, "local"))
+        temp.append(sys.prefix)
+        temp.append(os.path.join(sys.prefix, "local"))
     elif tail == "local":
         h, t = os.path.split(head)
         if t == "usr":
             # sys.prefix is /foo/usr/local;
             # check /foo/usr/local/lib/scons* first,
             # then /foo/usr/lib/scons*.
-            prefs.append(sys.prefix)
-            prefs.append(head)
+            temp.append(sys.prefix)
+            temp.append(head)
         else:
             # sys.prefix is /foo/local;
             # check only /foo/local/lib/scons*.
-            prefs.append(sys.prefix)
+            temp.append(sys.prefix)
     else:
         # sys.prefix is /foo (ends in neither /usr or /local);
         # check only /foo/lib/scons*.
-        prefs.append(sys.prefix)
+        temp.append(sys.prefix)
+
+    # suffix these to add to our original prefs:
+    prefs.extend([os.path.join(x, 'lib') for x in temp])
+    prefs.extend([os.path.join(x, 'lib', 'python' + sys.version[:3],
+                               'site-packages') for x in temp])
 
-    temp = [os.path.join(x, 'lib') for x in prefs]
-    temp.extend([os.path.join(x,
-                                           'lib',
-                                           'python' + sys.version[:3],
-                                           'site-packages') for x in prefs])
-    prefs = temp
 
     # Add the parent directory of the current python's library to the
-    # preferences.  On SuSE-91/AMD64, for example, this is /usr/lib64,
-    # not /usr/lib.
+    # preferences.  This picks up differences between, e.g., lib and lib64,
+    # and finds the base location in case of a non-copying virtualenv.
     try:
         libpath = os.__file__
     except AttributeError:
         pass
     else:
         # Split /usr/libfoo/python*/os.py to /usr/libfoo/python*.
-        libpath, tail = os.path.split(libpath)
+        libpath, _ = os.path.split(libpath)
         # Split /usr/libfoo/python* to /usr/libfoo
         libpath, tail = os.path.split(libpath)
         # Check /usr/libfoo/scons*.
         prefs.append(libpath)
 
 # Look first for 'scons-__version__' in all of our preference libs,
-# then for 'scons'.
-libs.extend([os.path.join(x, scons_version) for x in prefs])
-libs.extend([os.path.join(x, 'scons') for x in prefs])
+# then for 'scons'.  Skip paths that do not exist.
+libs.extend([os.path.join(x, scons_version) for x in prefs if os.path.isdir(x)])
+libs.extend([os.path.join(x, 'scons') for x in prefs if os.path.isdir(x)])
 
 sys.path = libs + sys.path
 
@@ -191,6 +195,7 @@ import imp
 
 import SCons.SConsign
 
+
 def my_whichdb(filename):
     if filename[-7:] == ".dblite":
         return "SCons.dblite"
@@ -221,24 +226,41 @@ def my_import(mname):
         fp, pathname, description = imp.find_module(mname)
     return imp.load_module(mname, fp, pathname, description)
 
+
 class Flagger(object):
     default_value = 1
+
     def __setitem__(self, item, value):
         self.__dict__[item] = value
         self.default_value = 0
+
     def __getitem__(self, item):
         return self.__dict__.get(item, self.default_value)
 
+
 Do_Call = None
 Print_Directories = []
 Print_Entries = []
 Print_Flags = Flagger()
 Verbose = 0
 Readable = 0
+Warns = 0
+
+
 
 def default_mapper(entry, name):
+    '''
+    Stringify an entry that doesn't have an explicit mapping.
+
+    Args:
+        entry:  entry
+        name: field name
+
+    Returns: str
+
+    '''
     try:
-        val = eval("entry."+name)
+        val = eval("entry." + name)
     except:
         val = None
     if sys.version_info.major >= 3 and isinstance(val, bytes):
@@ -248,7 +270,18 @@ def default_mapper(entry, name):
         val = val.decode()
     return str(val)
 
-def map_action(entry, name):
+
+def map_action(entry, _):
+    '''
+    Stringify an action entry and signature.
+
+    Args:
+        entry: action entry
+        second argument is not used
+
+    Returns: str
+
+    '''
     try:
         bact = entry.bact
         bactsig = entry.bactsig
@@ -256,7 +289,17 @@ def map_action(entry, name):
         return None
     return '%s [%s]' % (bactsig, bact)
 
-def map_timestamp(entry, name):
+def map_timestamp(entry, _):
+    '''
+    Stringify a timestamp entry.
+
+    Args:
+        entry: timestamp entry
+        second argument is not used
+
+    Returns: str
+
+    '''
     try:
         timestamp = entry.timestamp
     except AttributeError:
@@ -266,19 +309,38 @@ def map_timestamp(entry, name):
     else:
         return str(timestamp)
 
-def map_bkids(entry, name):
+def map_bkids(entry, _):
+    '''
+    Stringify an implicit entry.
+
+    Args:
+        entry:
+        second argument is not used
+
+    Returns: str
+
+    '''
     try:
         bkids = entry.bsources + entry.bdepends + entry.bimplicit
         bkidsigs = entry.bsourcesigs + entry.bdependsigs + entry.bimplicitsigs
     except AttributeError:
         return None
-    result = []
-    for i in range(len(bkids)):
-        result.append(nodeinfo_string(bkids[i], bkidsigs[i], "        "))
-    if result == []:
+
+    if len(bkids) != len(bkidsigs):
+        global Warns
+        Warns += 1
+        # add warning to result rather than direct print so it will line up
+        msg = "Warning: missing information, {} ids but {} sigs"
+        result = [msg.format(len(bkids), len(bkidsigs))]
+    else:
+        result = []
+    result += [nodeinfo_string(bkid, bkidsig, "        ")
+               for bkid, bkidsig in zip(bkids, bkidsigs)]
+    if not result:
         return None
     return "\n        ".join(result)
 
+
 map_field = {
     'action'    : map_action,
     'timestamp' : map_timestamp,
@@ -289,6 +351,7 @@ map_name = {
     'implicit'  : 'bkids',
 }
 
+
 def field(name, entry, verbose=Verbose):
     if not Print_Flags[name]:
         return None
@@ -299,6 +362,7 @@ def field(name, entry, verbose=Verbose):
         val = name + ": " + val
     return val
 
+
 def nodeinfo_raw(name, ninfo, prefix=""):
     # This just formats the dictionary, which we would normally use str()
     # to do, except that we want the keys sorted for deterministic output.
@@ -314,6 +378,7 @@ def nodeinfo_raw(name, ninfo, prefix=""):
         name = repr(name)
     return name + ': {' + ', '.join(l) + '}'
 
+
 def nodeinfo_cooked(name, ninfo, prefix=""):
     try:
         field_list = ninfo.field_list
@@ -321,15 +386,19 @@ def nodeinfo_cooked(name, ninfo, prefix=""):
         field_list = []
     if '\n' in name:
         name = repr(name)
-    outlist = [name+':'] + [_f for _f in [field(x, ninfo, Verbose) for x in field_list] if _f]
+    outlist = [name + ':'] + [
+        f for f in [field(x, ninfo, Verbose) for x in field_list] if f
+    ]
     if Verbose:
         sep = '\n    ' + prefix
     else:
         sep = ' '
     return sep.join(outlist)
 
+
 nodeinfo_string = nodeinfo_cooked
 
+
 def printfield(name, entry, prefix=""):
     outlist = field("implicit", entry, 0)
     if outlist:
@@ -343,13 +412,15 @@ def printfield(name, entry, prefix=""):
         else:
             print("        " + outact)
 
+
 def printentries(entries, location):
     if Print_Entries:
         for name in Print_Entries:
             try:
                 entry = entries[name]
             except KeyError:
-                sys.stderr.write("sconsign: no entry `%s' in `%s'\n" % (name, location))
+                err = "sconsign: no entry `%s' in `%s'\n" % (name, location)
+                sys.stderr.write(err)
             else:
                 try:
                     ninfo = entry.ninfo
@@ -369,6 +440,7 @@ def printentries(entries, location):
                 print(nodeinfo_string(name, entry.ninfo))
             printfield(name, entry.binfo)
 
+
 class Do_SConsignDB(object):
     def __init__(self, dbm_name, dbm):
         self.dbm_name = dbm_name
@@ -403,15 +475,17 @@ class Do_SConsignDB(object):
                     # Nope, that file doesn't even exist, so report that
                     # fact back.
                     print_e = e
-                sys.stderr.write("sconsign: %s\n" % (print_e))
+                sys.stderr.write("sconsign: %s\n" % print_e)
                 return
         except KeyboardInterrupt:
             raise
         except pickle.UnpicklingError:
-            sys.stderr.write("sconsign: ignoring invalid `%s' file `%s'\n" % (self.dbm_name, fname))
+            sys.stderr.write("sconsign: ignoring invalid `%s' file `%s'\n"
+                             % (self.dbm_name, fname))
             return
         except Exception as e:
-            sys.stderr.write("sconsign: ignoring invalid `%s' file `%s': %s\n" % (self.dbm_name, fname, e))
+            sys.stderr.write("sconsign: ignoring invalid `%s' file `%s': %s\n"
+                             % (self.dbm_name, fname, e))
             return
 
         if Print_Directories:
@@ -419,35 +493,44 @@ class Do_SConsignDB(object):
                 try:
                     val = db[dir]
                 except KeyError:
-                    sys.stderr.write("sconsign: no dir `%s' in `%s'\n" % (dir, args[0]))
+                    err = "sconsign: no dir `%s' in `%s'\n" % (dir, args[0])
+                    sys.stderr.write(err)
                 else:
                     self.printentries(dir, val)
         else:
             for dir in sorted(db.keys()):
                 self.printentries(dir, db[dir])
 
-    def printentries(self, dir, val):
-        print('=== ' + dir + ':')
+    @staticmethod
+    def printentries(dir, val):
+        try:
+            print('=== ' + dir + ':')
+        except TypeError:
+            print('=== ' + dir.decode() + ':')
         printentries(pickle.loads(val), dir)
 
+
 def Do_SConsignDir(name):
     try:
         fp = open(name, 'rb')
     except (IOError, OSError) as e:
-        sys.stderr.write("sconsign: %s\n" % (e))
+        sys.stderr.write("sconsign: %s\n" % e)
         return
     try:
         sconsign = SCons.SConsign.Dir(fp)
     except KeyboardInterrupt:
         raise
     except pickle.UnpicklingError:
-        sys.stderr.write("sconsign: ignoring invalid .sconsign file `%s'\n" % (name))
+        err = "sconsign: ignoring invalid .sconsign file `%s'\n" % (name)
+        sys.stderr.write(err)
         return
     except Exception as e:
-        sys.stderr.write("sconsign: ignoring invalid .sconsign file `%s': %s\n" % (name, e))
+        err = "sconsign: ignoring invalid .sconsign file `%s': %s\n" % (name, e)
+        sys.stderr.write(err)
         return
     printentries(sconsign.entries, args[0])
 
+
 ##############################################################################
 
 import getopt
@@ -489,8 +572,7 @@ for o, a in opts:
     elif o in ('-f', '--format'):
         # Try to map the given DB format to a known module
         # name, that we can then try to import...
-        Module_Map = {'dblite'   : 'SCons.dblite',
-                      'sconsign' : None}
+        Module_Map = {'dblite': 'SCons.dblite', 'sconsign': None}
         dbm_name = Module_Map.get(a, a)
         if dbm_name:
             try:
@@ -498,6 +580,7 @@ for o, a in opts:
                     dbm = my_import(dbm_name)
                 else:
                     import SCons.dblite
+
                     dbm = SCons.dblite
                     # Ensure that we don't ignore corrupt DB files,
                     # this was handled by calling my_import('SCons.dblite')
@@ -526,7 +609,6 @@ for o, a in opts:
     elif o in ('-v', '--verbose'):
         Verbose = 1
 
-
 if Do_Call:
     for a in args:
         Do_Call(a)
@@ -534,11 +616,12 @@ else:
     for a in args:
         dbm_name = whichdb(a)
         if dbm_name:
-            Map_Module = {'SCons.dblite' : 'dblite'}
+            Map_Module = {'SCons.dblite': 'dblite'}
             if dbm_name != "SCons.dblite":
                 dbm = my_import(dbm_name)
             else:
                 import SCons.dblite
+
                 dbm = SCons.dblite
                 # Ensure that we don't ignore corrupt DB files,
                 # this was handled by calling my_import('SCons.dblite')
@@ -548,6 +631,8 @@ else:
         else:
             Do_SConsignDir(a)
 
+    if Warns:
+        print("NOTE: there were %d warnings, please check output" % Warns)
 sys.exit(0)
 
 # Local Variables: