@Robie Basak
The main problem is that all the packages that rely on an active mysql-server to upgrade themselves will stop and ask what to do, thus you anyway need to babysit them :)
At this point, having the upgrade of Mysql-Server stopping if it was on and could not restart will only stop the upgrade once.
I don't think a release upgrade has to be done unattended...
@Robie Basak
The main problem is that all the packages that rely on an active mysql-server to upgrade themselves will stop and ask what to do, thus you anyway need to babysit them :)
At this point, having the upgrade of Mysql-Server stopping if it was on and could not restart will only stop the upgrade once.
I don't think a release upgrade has to be done unattended...