mutex unlock check timeout to avoid double unlock.

lichao

2021-04-23 a04d4d01eb8e38b8ec5367114b5581bd64eee17e

 src/failed_msg.cpp

@@ -23,7 +23,7 @@
   return [remote, msg](void *valid_sock) mutable {
      assert(valid_sock);
      ShmSocket &sock = *static_cast<ShmSocket *>(valid_sock);
      DEFER1(msg.Release(sock.shm())); // Release() is not const, but it's safe to release.
      DEFER1(msg.Release()); // Release() is not const, but it's safe to release.
      return sock.Send(remote.data(), msg);
   };
}