Protect against crash in the `relation_possible` predicate with ambiguous relations.
It was still possible to get a KeyError when using relations that are ambiguous
at both ends, like (Executable, version_of, Program) & (Version, version_of, Project).
Closes #3010148.
for eschema in schema.entities():
if not (eschema.final or 'cw_source' in eschema.subjrels):
add_relation_definition(eschema.type, 'cw_source', 'CWSource', ask_confirm=False)
sql('INSERT INTO cw_source_relation(eid_from, eid_to) '
'SELECT e.eid,s.cw_eid FROM entities as e, cw_CWSource as s '
'WHERE s.cw_name=e.source AND NOT EXISTS(SELECT 1 FROM cw_source_relation WHERE eid_from=e.eid AND eid_to=s.cw_eid)')
commit()