[1.0.X] Replace test use of assertTrue with failUnless. No matter how many...

[1.0.X] Replace test use of assertTrue with failUnless. No matter how many times we try, Python 2.3 still doesn't recognize assertTrue.

[10390] from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10391 bcc190cf-cafb-0310-a4f2-bffc1f526a37