AdminSite app_index does work it doesn't need to

[Keryn Knight <django@…>]

If a user doesn't have permissions to a module (as defined by it's app label), the way the ​app_index works, it will still go through the motions of iterating the modeladmin registry and checking permissions it knows cannot be true, as far as I can see. Having done all that, if the app_dict is empty [and it should be], it ​throws a 404, whereas the ModelAdmin views themselves tend to ​raise PermissionDenied. The fix is pretty simple, and actually simplifies the view, if you believe shallow trumps deep.

Marking as has patch on the basis on an incoming GitHub pull request.

[Keryn Knight <django@…>]

​Pull request is here, tests pass locally based on the following command:

PYTHONPATH=..:$PYTHONPATH python ./runtests.py --settings=test_sqlite admin_views.tests.AdminViewPermissionsTest

[Tim Graham <timograham@…>]

In 0d74f9553c6acb8b53a502ca5e39542dcc4412c1:

Fixed #21063 -- AdminSite app_index should be fail early if the user has no permissions.