neo4j/neo4j — pull request #1100 by boggle (2013-08-22 16:15:59+00:00)
Title: 2.0 optional actions

This changes Cypher to skip any write clause that references an unbound node introduced via an optional relationship, i.e. START n=... MATCH (n)-[?r]-(m) SET m.foo=12 will not do anything if r (and thus m) are not bound.