python27: support test/support

In the maintenance release bump in
90059701 a certain change to /test/ was
backported from Python 3:

- bpo-30207: To simplify backports from Python 3, the test.test_support
  module was converted into a package and renamed to test.support.  The
  test.script_helper module was moved into the test.support package.
  Names test.test_support and test.script_helper are left as aliases to
  test.support and test.support.script_helper.