Symbiosis: MariaDB breaks phpMyAdmin authentication in Stretch
Imported from https://www.github.com/BytemarkHosting/symbiosis/issues/126
MariaDB uses unix socket authentication by default, rather than username/password. As such, phpMyAdmin HTTP authentication won't accept the credentials for the root@localhost MySQL user.
Likely fix would be to either disable unix socket auth, or create an additional MySQL user which uses username/password authentication.