[debian-mysql] Bug#990306: bug on mariadb-server version 1:10.3.29-0+deb10u1

[Jacopo D'oro]

Package: mariadb-server
Version: 1:10.3.29-0+deb10u1

In the last upgrade of maridb-server package for debian buster (version 
1:10.3.29-0+deb10u1), the following bug is now affecting any system that 
installed the update:

https://jira.mariadb.org/browse/MDEV-25714

This bug has been fixed in version 10.3.30 and has been marked as 
emercency because is compromising the results of some type of queries 
(subqueries with group by).
An update or a rollback is necessary, a workaroud suggested by Mariadb 
is also available (optimizer_switch='split_materialized=off')