Merges server/lib/classes/db_mysql.inc.php with interface/lib/classes/db_mysql.inc.php and updates everywhere that uses the db class. MySQL flags (ie. SSL support) now work on both the local db and dbmaster connections.
This does not address install/lib/mysql.lib.php. Also server/plugins-available/mysql_clientdb_plugin.inc.php has it's own set of mysql connection code for creating/managing databases and database users, which has not been updated (it could (should?) use the db class from server/lib/classes/db_mysql.inc.php)
See https://www.howtoforge.com/community/threads/server-vs-interface-db_mysql-inc-php.79593/