Fixed #1931 -- update_object generic view no longer assumes the object's...

Fixed #1931 -- update_object generic view no longer assumes the object's get_absolute_url() doesn't change. Thanks, marcink@elksoft.pl

git-svn-id: http://code.djangoproject.com/svn/django/trunk@2951 bcc190cf-cafb-0310-a4f2-bffc1f526a37