If the authoritative region has been upgraded to a version of Nomad that has new
replicated objects (such as ACL Auth Methods, ACL Binding Rules, etc.), the
non-authoritative regions will start replicating those objects as soon as their
leader is upgraded. If a server in the non-authoritative region is upgraded and
then becomes the leader before all the other servers in the region have been
upgraded, then it will attempt to write a Raft log entry that the followers
don't understand. The followers will then panic.
Add same the minimum version checks that we do for RPC writes to the leader's
replication loop.
