[1.1.X] Fixed #13309 -- Ensure that delete() deletes everything it should...

[1.1.X] Fixed #13309 -- Ensure that delete() deletes everything it should delete(). Thanks to craig.kimerer@gmail.com for the report

Backport of r12941 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12955 bcc190cf-cafb-0310-a4f2-bffc1f526a37