master PR: https://github.com/hibernate/hibernate-orm/pull/1281
PR skips NationalizedIgnoreCaseTest on db2 and postgresql. It can't skip test on maridb, because there is no mariadb dialect and mysql dialect is used with mariadb. If there is a way how to distinguish these two databases, please let me know and I'll update PR.

Could you please also cherry-pick fix to 5.0?