cubicweb #1631282 Incorrect fetch_attrs under certain conditions [resolved]

When a relation is in fetch_attrs but target etypes that have themselves different fetched attributes, only first etype is considered. This can lead to incorrect generated RQL: if a relation (or attribute) is not defined in the second etype but only in the first one, entities of the second etype will never be reached as generated RQL will include the relation in its restriction list.

done in3.12.3
load left0.000
closed by#c281afe35b8b [entity] fix entity fetch_rql when fetch_attrs contains a rtype with multiple destination etypes which do not have the same fetched attributes themselves (closes #1631282)