Updated test assertions that have been deprecated by the move to unittest2. In summary, this means:

 assert_ -> assertTrue
 assertEquals -> assertEqual
 failUnless -> assertTrue

For full details, see http://www.voidspace.org.uk/python/articles/unittest2.shtml#deprecations

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15728 bcc190cf-cafb-0310-a4f2-bffc1f526a37