[login form] Fix BaseLogForm.form_action() The method implementation was calling super() with the wrong class

[migration] move 'entities' table changes from 3.19.0 to bootstrap script The 'mtime' and 'source' columns need to go away before we attempt to do anything else with the repo, otherwise any addition of an entity is going to explode.

[server/session] add missing rollback when freeing a db connection When we let go of a cnxset and give it back to the pool, we need to make sure it's not in the middle of a transaction. We got bitten by a migration where the connection used by admin's repo.connect was not rolled back before attempting the migration, causing a deadlock because it had a lock on a table. This could potentially also be an issue for e.g. hooks or looping tasks that didn't explicitly rollback before calling free_cnxset or moving out of a ensure_cnx_set block.