During Failover Passive MaxScale route writes to the Old Master

In an Active/Passive MaxScale setup, a failover process can occur. During this process, the old master may come back online and be identified by the Passive MaxScale as the Master. In this event, writes may be routed to the old master. However, if the failover process completes in the Active MaxScale and the old master tries to rejoin the cluster as a slave, replication fails. This is because there could be writes routed by Passive MaxScale that occurred in the old master during the failover process.