Log Message:
Update to 0.2.12. Changes:

- Fixed a corner case where depending on the order of events when installing
  multiple packages (i.e. when installing packages with dependencies, some
  of which might also use d2to1) we would end up calling the incorrect
  Distribution class (the patched version from setuptools, where d2to1
  needs to get to the unpatched version from distutils for some cases).

- Upgraded bundled copy of the ``six`` module to the current version
  (1.9.0).  This fixes incompatibility between d2to1 and other packages
  that import different versions of ``six`` during their setup (the older
  version of ``six`` had a habit of fighting with other ``six`` instances
  over ``sys.modules``, which is fixed in newer versions).

- Upgraded to latest ``ez_setup.py`` so that the most up to date version
  of setuptools will be correctly bootstrapped in the rare cases that it
  is needed.

- Included some miscellaneous hacks to keep d2to1 working, nominally, with
  Python 2.5 despite the broad move away from Python 2.5 support in the
  Python community.  The d2to1 v0.2.x releases will be the last to continue
  Python 2.5 support, given that testing it has become more difficult (and
  the overhead is probably no longer worth it).