Restore task does not drop database before importing backup
If restoring a backup to a fresh installation, there is no issue. However, if a user tries to upgrade, runs in to a problem, downgrades and tries to restore a backup the database will be left in a weird state. Namely, the database will still contain new tables. On next upgrade, the migrations will fail because tables already exist.
To prevent this we should drop the database before importing it. Also, because this will continue to be a problem until people upgrade past the fix point, we should document what to do if you have these migrations errors.