message: Log path rebinding errors in abstract_downstream
diff: @@ -81,6 +81,8 @@ bool abstract_downstream::confirm_path(const strong_actor_ptr& rebind_from,
  (*i)->hdl = ptr;
  return true;
  }
  + CAF_LOG_INFO("confirming path failed" << CAF_ARG(rebind_from)
  + << CAF_ARG(ptr));
  return false;
  }
  