New submission from Nick Coghlan <ncoghlan@gmail.com>:
Add test.support.import_python_only as per
http://mail.python.org/pipermail/python-dev/2009-February/086387.html
Also add an equivalent to test.test_support in 2.x (I haven't checked
yet if importlib is available in 2.x, so the implementation may need to
be a little different)