message: Try to fix track mix
diff: // author: Bong-Hwi Lim (bong-hwi.lim@cern.ch)
  // , Beomkyu KIM (kimb@cern.ch)
  //
  -// Last Modified Date: 2019/07/16
  +// Last Modified Date: 2019/07/20
  //
  ////////////////////////////////////////////////////////////////////////////
  @@ -775,8 +775,10 @@ Bool_t AliAnalysisTaskXi1530::GoodTracksSelection() {
  goodtrackindices.push_back(it);
  // Event mixing pool
  - if (fsetmixing)
  - etl->push_back((AliVTrack*)track->Clone());
  + if (fsetmixing){
  + AliVTrack* track_mix = (AliVTrack*)fEvt->GetTrack(it);
  + etl->push_back((AliVTrack*)track_mix->Clone());
  + }
  }
  if (fsetmixing) {
  