Details
Major Description
It's currently possible to add a peer for replication and point it to the local cluster, which I believe could very well happen for those like us that use only one ZK ensemble per DC so that only the root znode changes when you want to set up replication intra-DC.
I don't think comparing just the cluster ID would be enough because you would normally use a different one for another cluster and nothing will block you from pointing elsewhere.
Comparing the ZK ensemble address doesn't work either when you have multiple DNS entries that point at the same place.
I think this could be resolved by looking up the master address in the relevant znode as it should be exactly the same thing in the case where you have the same cluster.