qso_cat_utils doesn't update ZWARN when overwriting Z

[abrodze]

In constructing the QSO catalog, only the Z and ZERR columns are updated for QN-identified objects. The ZWARN and other redrock attributes remain from the initial run and therefore have little meaning. As a part of a larger cleanup of the QN afterburner, we plan to save more info from the post-QN redrock rerun which can be used to address this issue.

Related Issues: #2299, #2398, #2397, #2281

[moustakas]

@abrodze, I think this ticket was addressed with #144. If so, is it safe to close this?