Server can be member of a cluster and slave of another node inside that cluster at the same time

After converting a master slave configuration to a cluster by changing the config and bootstrapping the cluster by the previous master the other nodes still have the slave configuration and start the slave against the former master although they are already connected to that server via Galera. In case a server joins a cluster and still has a slave configuration it should recognize that the master of that slave config is another node and deactive it.