Fixed #8882 -- When a foreign key is among the unique_together fields in an...

Fixed #8882 -- When a foreign key is among the unique_together fields in an inline formset properly handle it.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9297 bcc190cf-cafb-0310-a4f2-bffc1f526a37