Fixed #12554 again: Corrected regression in silencing attribute lookups...

Fixed #12554 again: Corrected regression in silencing attribute lookups introduced in r12823, plus added a test for this so it doesn't regress again.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@12834 bcc190cf-cafb-0310-a4f2-bffc1f526a37