[multi-sources] closes #1918120: drop behaviour leading to wrong result as demonstrated by the ticket
The formerly implemented behaviour doesn't seems to be useful,
nor to have a chance to be correct. At least no test case demonstrate
the opposite, so I've dropped it.
# type attribute might already be there if migrating from
# version < 3.5 to version >= 3.5.3, BaseTransition being added
# in bootstrap_migration
if versions_map['cubicweb'][0] >= (3, 5, 0):
add_attribute('BaseTransition', 'type')
sync_schema_props_perms('state_of')
sync_schema_props_perms('transition_of')