Not possible to cleanly remove actors from supervision group

I am listening to a cluster of servers using Celluloid actors, the cluster can change, so I need to be able to dynamically add and remove actors as servers go up and down, but unless it changes I want the actors to restart if they crash.

I've created a supervision group, which keeps track of which servers need to be watched and I can add actors to this group, unfortunately there isn't a good way to remove actors from the group in case one server goes down. Supervision groups don't seem to have a way to remove actors from their list of members.

Terminating an actor using `terminate` doesn't seem to be safe, since it leaks members in the supervision group.