Fixed test failure that was occurring since r12909

  
The tests were relying on being able to do
ManyToManyField("NameOfThisModel") instead of the only documented method for
recursive relationships, namely ManyToManyField("self").  The former stopped
working when the fix in r12909 was applied.

Backport of r12932 from trunk


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12933 bcc190cf-cafb-0310-a4f2-bffc1f526a37