message: Log warning if we received fetch response for no responder.
diff: @@ -198,7 +198,17 @@ pub(crate) trait ItemFetcher<T: Item + 'static> {
  peer: NodeId,
  ) -> Effects<Event<T>> {
  let mut effects = Effects::new();
  - let mut all_responders = self.responders().remove(&id).unwrap_or_default();
  + let mut all_responders = match self.responders().remove(&id) {
  + Some(responders) => responders,
  + None => {
  + warn!(
  + ?id,
  + ?peer,
  + "received an item that no responder is waiting for"
  + );
  + return Effects::new();
  + }
  + };
  match result {
  Ok(item) => {
  // Since this is a success, we can safely respond to all awaiting processes.
  @@ -702,7 +712,7 @@ where
  }
  Event::RejectedRemotely { .. } => Effects::new(),
  Event::AbsentRemotely { id, peer } => {
  - info!(TAG=%T::TAG, %id, %peer, "item absent on the remote node");
  + info!(TAG=%T::TAG, ?id, %peer, "item absent on the remote node");
  self.signal(id, Err(FetcherError::Absent { id, peer }), peer)
  }
  Event::TimeoutPeer { id, peer } => {
  