Merge in default (move from stable to default; we need to change the protocol)
In fact, that case can't happen since bug 26043, so let's simplify.
Switch to having the winner inform the losers that they need to stop, rather than having the leader do it. This fixes the race where the leader tells them to stop before the partition has healed from the winner's POV. So it should be simpler and more correct.
Check whether the cluster is fully connected before trying to autoheal, and ignore autoheal requests if it isn't.
Be a bit less verbose here: it's actually a very common case and perfectly normal; no need to dump state.
Just in case something goes wrong in our weird unsupervised process, log it.
Merge bug26368