the upgrade failed because notification_user_map constraint notif_user_map_notif_id_fk needed the pk on notifications_bak, now drops it and recreates it after the table is reloaded
Another partial fix for #1144: join on rel_id, too, so when a user has two rows in cc_users he only shows up twice, not four times (cartesian product of all the relations)
Fix for #1144: duplicate rows in cc_users. group::add_member will now delete any memberhip_rel or child thereof before inserting the new relation. It didn't before, and this could cause a user to have both a membership_rel and an admin_rel relation to the registered_users group.