Merged revisions 66171 via svnmerge from

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  r66171 | amaury.forgeotdarc | 2008-09-03 01:19:56 +0200 (mer., 03 sept. 2008) | 9 lines

  Issue 2975: when compiling multiple extension modules with visual studio 2008
  from the same python instance, some environment variables (LIB, INCLUDE)
  would grow without limit.

  Tested with these statements:
      distutils.ccompiler.new_compiler().initialize()
      print os.environ['LIB']
  But I don't know how to turn them into reliable unit tests.
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