Comment 22 for bug 1638125

Regarding ironstorm's note in #21, we didn't realize our /var/lib/mysql folder was moved to /tmp/mysql-symlink-restore-forbvv/.

Apparently a previous upgrade of mysql-5.7 left /var/lib/mysql-upgrade/ in place with a DATADIR symlink to 'mysql-5.7'. This confused mariadb-server-10.0.postinst [1] and triggered the "# this should never even happen, but just in case..." block. Neither ironstorm or I noticed that our /var/lib/mysql folder had been moved into /tmp, so we thought it had been lost.

Glad to not have data loss, but pretty spooked. /tmp does not seem like a very good place for this since it could be automatically wiped.

[1] https://fossies.org/linux/mariadb/debian/dist/Debian/mariadb-server-10.0.postinst