Fixed #10733 -- Added a regression test for queries with multiple references...

Fixed #10733 -- Added a regression test for queries with multiple references to multiple foreign keys in only() clauses. Thanks to mrts for the report.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10928 bcc190cf-cafb-0310-a4f2-bffc1f526a37