The butler changes in
DM-4683, in particular the removal of .mapper from the interface exposed by a Butler object, broken obs_cfht, obs_decam, and ci_hsc.
This issue will fix those changes, and search for additional broken things.
This work is proceeding in conjunction with
DM-5370 to test that the CI system, e.g. lsst_ci, is sensitive to these breakages and fixes.