It's possible to roll back a database migration manually by using SQL.
One major pain is updating the version info in the json schema blob.

However it would be useful to be able to do this from roundup-admin.

Maybe a 'roundup-admin db migrateto 7' to run db migration to go from whatever is
current to version 7?

Once it performs the migration it should exit.

The user is then expected to run a prior version of Roundup against the tracker.

This goes along with allowing roundup-admin to act as a limited db client. E.G. allow
it to set log style (WAL/delete) on a sqlite db.