[1.0.X] Fixed #11042 -- Corrected admin inlines for inherited models. Thanks...

[1.0.X] Fixed #11042 -- Corrected admin inlines for inherited models. Thanks to jsmullyan for the report, and mir for helpful triage work. Patch includes regression test for #8093, and a commented out test for #10992.

Merge of r10725 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10726 bcc190cf-cafb-0310-a4f2-bffc1f526a37