When talking about T161232, I noticed that although we check mysqlDBMS version at install time, we don't seem to check it again.
I'm not suggesting we need to check it on every page view, like we do with PHP, but I think we should be checking it and confirming it's correct when running update.php; an action that would be done after upgrading MW php files, which could bring a bump in the near future if T161232 goes ahead