Fixed #16716 -- Fixed two small regressions in the development version...

Fixed #16716 -- Fixed two small regressions in the development version introduced in r16144 where the changelist crashed with a 500 error instead of nicely operating a 302 redirection back to the changelist.

The two specific cases were:

* a lookup through a non-existing field and apparently spanning multiple relationships (e.g. "?nonexistant__whatever=xxxx").
* a proper list_filter's queryset failing with an exception. In Django 1.3 the queryset was only directly manipulated by the changelist, whereas in 1.4 the list_filters may manipulate the queryset themselves. The fix here implies catching potential failures from the list_filters too.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16705 bcc190cf-cafb-0310-a4f2-bffc1f526a37