Admin: Trying to log in with incorrect information fails without an error
Description
1. Go to https://test.archiveofourown.org/admin/login
2. Enter your admin user name and the wrong password, or enter both wrong
3. Press "Log in as admin"
What happens
The log in page just reloads and, if your connection is fast, you're left going, "Wait, did it even do anything?"
What should happen instead
You should get a red error message telling me, "The password or admin user name you entered doesn't match our records."
