bugifx for using compute chunk/atom with compress via rerun or right at the beginning of a run

    return;

  }

  invoked_ichunk = update->ntimestep;

  // assign chunk IDs to atoms

  // will exclude atoms not in group or in optional region

  // already invoked if this is same timestep as last setup_chunks()

  // however, when between runs or using rerun, we need it again.

  if (update->ntimestep > invoked_setup) assign_chunk_ids();

  if ((update->ntimestep > invoked_setup) || (invoked_ichunk < 0)) assign_chunk_ids();

  invoked_ichunk = update->ntimestep;

  // compress chunk IDs via hash of the original uncompressed IDs

  // also apply discard rule except for binning styles which already did