Don't clear write interest if pending_response_queue_ non empty

src/connection.cpp

@@ -295,7 +295,7 @@ uint32_t Connection::write_bytes() {
   // Check if queue is empty and remove EPOLLOUT interest
   {
     std::lock_guard lock(mutex_);
-    if (message_queue_.empty()) {
+    if (message_queue_.empty() && pending_response_queue_.empty()) {
       auto server = server_.lock();
       if (server) {
         struct epoll_event event;