It looks like the following mysql default config files have to be changed: /etc/mysql/mysql.d/50-distro-client.cnf /etc/mysql/mysql.d/50-distro-server.cnf /var/run/ -> /run/ See bug #768051.
Also see bug #766138.
I think this is already covered in the other bug. *** This bug has been marked as a duplicate of bug 768051 ***