[1.0.X] Fixed #10589 -- Removed duplicated model definition in...

[1.0.X] Fixed #10589 -- Removed duplicated model definition in null_fk_ordering regression test. Thanks to Julien Phalip for the report.

Merge of r10143 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10153 bcc190cf-cafb-0310-a4f2-bffc1f526a37