Patched the new version of SCons to work around a Mac+Python+Toolchain bug.

scons-2.0.1/script/scons

 #! /usr/bin/env python
 #
 # SCons - a Software Constructor
 #
 # Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 The SCons Foundation
 #
 # Permission is hereby granted, free of charge, to any person obtaining
 # a copy of this software and associated documentation files (the
 # "Software"), to deal in the Software without restriction, including
 # without limitation the rights to use, copy, modify, merge, publish,
@@ skipping 143 matching lines @@
     else:
         # Split /usr/libfoo/python*/os.py to /usr/libfoo/python*.
         libpath, tail = os.path.split(libpath)
         # Split /usr/libfoo/python* to /usr/libfoo
         libpath, tail = os.path.split(libpath)
         # Check /usr/libfoo/scons*.
         prefs.append(libpath)
 
     try:
         import pkg_resources
-    except ImportError:
+    # BEGIN MODIFICATION
+    # It is known that importing pkg_resources can result in:
+    # An ImportError or
+    # A distutils.errors.DistutilsPlatformError
+    # (See: http://bugs.python.org/issue9516)
+    # The upstream version of SCons only catches an ImportError.
+    # The other exception gets throw on the Mac toolchain bot because it
+    # sets MACOSX_DEPLOYMENT_TARGET to an older version.
+    # In practice, it doesn't matter why importing pkg_resources fails, so
+    # it's reasonable to catch every exception.
+    except Exception:
+    # END MODIFICATION
         pass
     else:
         # when running from an egg add the egg's directory 
         try:
             d = pkg_resources.get_distribution('scons')
         except pkg_resources.DistributionNotFound:
             pass
         else:
             prefs.append(d.location)
 
@@ skipping 12 matching lines @@
     import SCons.Script
     # this does all the work, and calls sys.exit
     # with the proper exit status when done.
     SCons.Script.main()
 
 # Local Variables:
 # tab-width:4
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=4 shiftwidth=4: