Cypher : Merge with no param should merge the first match, not create a new one

[ExtReMLapin]

Executing this query with Cypher :

MERGE (n:PIPELINE_CONFIG) ON CREATE SET n.pipelines = ["miaou"] ON MATCH SET n.pipelines = ["miaou"] RETURN n.pipelines as pipelines

Should just overwrite the first found (here create one or merge/replace the only other/first found node existing) node PIPELINE_CONFIG.

It works with old cypher engine, but with new one, it just creates a new node again and again.

[ExtReMLapin]

pr : #3255

[lvca]

Thanks for the pr.