I'm not sure why the author removed this functionality. I don't know how it was originally implemented (whether you could specify the login or id of the account to always allow).
But I've implemented the same functionality in the most simple way, always allowing user id 1 to log in regardless of security setting. If you've never changed anything, I believe the admin account created at site creation time will always be 1. If it's different for your setup, it's easy enough to change the id in this patch.