Recently we migrate to mariadb and every version upgrade failed (last failed from 10.0.6 to 10.0.7). After investigation I find this thread http://mirzmaster.wordpress.com/2009/01/16/mysql-access-denied-for-user-debian-sys-maintlocalhost/ and after password update issue fixed. I find bug https://bugs.launchpad.net/maria/+bug/983322 but it marked as incomplete