message: Don't overwrite exit reason in down msg handler
diff: @@ -181,8 +181,6 @@ void basp_broker_state::purge_state(const node_id& nid) {
  void basp_broker_state::send_kill_proxy_instance(const node_id& nid,
  actor_id aid, error rsn) {
  CAF_LOG_TRACE(CAF_ARG(nid) << CAF_ARG(aid) << CAF_ARG(rsn));
  - if (rsn == none)
  - rsn = exit_reason::unknown;
  auto path = instance.tbl().lookup(nid);
  if (!path) {
  CAF_LOG_INFO("cannot send exit message for proxy, no route to host:"
  