message: Make client reader locking more consistent
diff: @@ -169,8 +169,9 @@ impl Client {
  // If flushing fails, disconnect.
  if res.is_err() {
  // NB see locking protocol for state.write and state.read
  - let mut read = client.state.read.lock();
  write.writer = None;
  +
  + let mut read = client.state.read.lock();
  read.pongs.clear();
  }
  }
  