[1.0.X] Fixed #10651: fixed a javascript error on the admin user add form....

[1.0.X] Fixed #10651: fixed a javascript error on the admin user add form. Thanks, seanl. Backport of [10714] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10715 bcc190cf-cafb-0310-a4f2-bffc1f526a37