Hello! Thanks for reporting.
The file /etc/mysql/debian-start is shipped as part of the mariadb-server-10.1 package: https://packages.debian.org/stretch/amd64/mariadb-server-10.1/filelist This has been the case for about 4 years and there has not been any recent changes to this: https://salsa.debian.org/mariadb-team/mariadb-10.1/blame/stretch/debian/mariadb-server-10.1.install I would be surprised if a fresh install, the most typical use case, would be broken. Are you sure the install is really fresh? I have no idea how this could have happened. I'd appreciate if you dig deeper. There is an upcoming stable update to MariaDB so if there is a problem, it would get fixed and shipped soon.
