Problem with inactive users that are from external authentication system

[hmiguim]

Steps to replicate:

1. Enable External authentication
2. Login (user1)
3. Deactivate the user1 previously created during the login
4. Try to login again with user1

Since user1 is deactivated the login flow doesn't have the correct behaviour. Redirects you to a blank page where you can not perform any actions. More over, the user appears to be logged in, but since it is deactivated cannot perform any actions.