[repo, hooks] small task optimization: don't start cleanup_old_transactions when undo support is not activated, and retrieve a session to update a source only when some source to update is found
# type attribute might already be there if migrating from# version < 3.5 to version >= 3.5.3, BaseTransition being added# in bootstrap_migrationifversions_map['cubicweb'][0]>=(3,5,0):add_attribute('BaseTransition','type')sync_schema_props_perms('state_of')sync_schema_props_perms('transition_of')