==================
- Modify the testrunner to use the standard Python ``doctest`` module instead
of the deprecated ``zope.testing.doctest``.
- Fix ``testrunner-leaks.txt`` to use the ``run_internal`` helper, so that
``sys.exit`` isn't triggered during the test run.
- Add support for conditionally using a subunit-based output
formatter upon request if subunit and testtools are available. Patch
contributed by Jonathan Lange.