Make the GROUP_CONCAT aggregate function not repeat values (closes #3223975) Work on sets instead of arrays, so if the same value appears twice it's not repeated in the concatenated output. This patch handles the postgresql and sqlite backends, mysql is left alone at this point (seems doable, but I don't have time or motivation to fix and test it).

sync_schema_props_perms('CWSourceHostConfig', syncperms=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()