Allow callbacks to update their list of workers

We need this to be able to allow coordinators to replace nodes that are
in maintenance mode.

BugzId: 22729
diff --git a/src/rexi_utils.erl b/src/rexi_utils.erl
index 79db48c..6e03757 100644
--- a/src/rexi_utils.erl
+++ b/src/rexi_utils.erl
@@ -49,6 +49,8 @@
     case process_message(RefList, Keypos, Fun, Acc0, TimeoutRef, PerMsgTO) of
     {ok, Acc} ->
         process_mailbox(RefList, Keypos, Fun, Acc, TimeoutRef, PerMsgTO);
+    {new_refs, NewRefList, Acc} ->
+        process_mailbox(NewRefList, Keypos, Fun, Acc, TimeoutRef, PerMsgTO);
     {stop, Acc} ->
         {ok, Acc};
     Error ->