Comment 25 for bug 1794588

Force-pushed a new version of the collab/phasefx/lp1794588-callnumber-edit2 branch.

Three cases here:
  1) We're editing a volume, and not its copies.
  2) We're editing a volume, and a subset of its copies.
  3) We're editing a volume, and all of its copies.

For 1) and 3), we definitely want to edit the volume
itself (and possibly auto-merge), but for 2), we want
to create a new volume (and possibly auto-merge).