Fixed #11513 -- Ensure that the redirect at the end of an object change won't redirect to a page for which the user doesn't have permission. Thanks to rlaager for the report and draft patch, and to Julien Phalip for the final patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@15584 bcc190cf-cafb-0310-a4f2-bffc1f526a37