Updating clustername broken

[JJWTimmer]

ml = MarkLogic(conn)
cluster = ml.cluster()
cluster.set_cluster_name(cl_config['cluster'])
cluster.update()

gives error

marklogic.exceptions.UnexpectedManagementAPIResponse: {"errorResponse":{"statusCode":"500", "status":"Internal Server Error", "messageCode":"XDMP-AS", "message":"XDMP-AS: (err:XPTY0004) $value as xs:string -- Invalid coercion: <opsdirector-session-endpoint xmlns=\"http://marklogic.com/manage/cluster-local/properties\"/> as xs:string"}}