Fixed a sloppy test auth test. [10400] revealed that the auth test was relying...

Fixed a sloppy test auth test. [10400] revealed that the auth test was relying on the weird difference between calling a management from the shell and from `call_command`. That this worked in the first case was pretty much an accident.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10404 bcc190cf-cafb-0310-a4f2-bffc1f526a37