[1.2.X] Fixed #14012 (again) -- Admin app: Don't show the full user edition...

[1.2.X] Fixed #14012 (again) -- Admin app: Don't show the full user edition view after adding a user in a FK popup. Thanks dburke for reporting this regression introduced in r14628.

Backport of [15637] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15638 bcc190cf-cafb-0310-a4f2-bffc1f526a37