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.
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.

pypa/setuptools,pypa/setuptools,pypa/setuptools