This fixes a broad class of bugs involving filters that look for missing
related models and fields. Most of them don't seem to have been reported
(the added tests cover the root cause). The exception is that this has
also fixed#9868.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@9979 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Many thanks to:
* Nicolas Lara, who worked on this feature during the 2008 Google Summer of Code.
* Alex Gaynor for his help debugging and fixing a number of issues.
* Malcolm Tredinnick for his invaluable review notes.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@9792 bcc190cf-cafb-0310-a4f2-bffc1f526a37