message: Fix exit reason propagation in monitorable_actor
diff: @@ -91,10 +91,10 @@ bool monitorable_actor::cleanup(error&& reason, execution_unit* host) {
  if (!set_fail_state)
  return false;
  CAF_LOG_DEBUG("cleanup" << CAF_ARG(id())
  - << CAF_ARG(node()) << CAF_ARG(reason));
  + << CAF_ARG(node()) << CAF_ARG(fail_state_));
  // send exit messages
  for (attachable* i = head.get(); i != nullptr; i = i->next.get())
  - i->actor_exited(reason, host);
  + i->actor_exited(fail_state_, host);
  // tell printer to purge its state for us if we ever used aout()
  if (getf(abstract_actor::has_used_aout_flag)) {
  auto pr = home_system().scheduler().printer();
  