SERVER-40441 made arbiters not try to create session collection or check if it exists. To check if a node is an arbiter, the LogicalSessionCacheImpl calls ReplicationCoordinator::getMemberState. In the case of standalones, this function returns RS_PRIMARY in 4.6 and 4.4 but throws UASSERT_NOT_IMPLEMENTED in 4.2 and earlier. To avoid the error and be consistent, we should call ReplicationCoordinator::isReplEnabled before calling ReplicationCoordinator::getMemberState() in all versions.