MariaDB packages can't be installed, tests fail in buildbot

+ sudo sh -c 'DEBIAN_FRONTEND=noninteractive MYSQLD_STARTUP_TIMEOUT=180 apt-get install --allow-unauthenticated -y libmariadbclient18 libmariadbclient-dev libmariadbd19 libmariadbd-dev libmysqlclient18 mariadb-client-10.2 mariadb-client mariadb-client-core-10.2 mariadb-common mariadb-plugin-cassandra mariadb-plugin-connect mariadb-plugin-cracklib-password-check mariadb-plugin-gssapi-client mariadb-plugin-gssapi-server mariadb-plugin-mroonga mariadb-plugin-oqgraph mariadb-plugin-spider mariadb-plugin-tokudb mariadb-server-10.2 mariadb-server mariadb-server-core-10.2 mariadb-test mariadb-test-data mysql-common'

...

Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable

distribution that some required packages have not yet been created

or been moved out of Incoming.

The following information may help to resolve the situation:

The following packages have unmet dependencies:

 libmariadbd19 : Breaks: libmysqld-dev

E: Unable to correct problems, you have held broken packages.