The warning that was added on DM-20937 says this code is “to be removed after v20”, not before. Will update blockers on this ticket appropriately.

Done as a pair-coding exercise with Clare Saunders

The Jenkins build has passed successfully: https://ci.lsst.codes/blue/organizations/jenkins/stack-os-matrix/detail/stack-os-matrix/32799/pipeline

John Parejko  Can get to this review sometime before Arun gets back next week? If not, I'll reassign.  This is a release blocker.

I made a comment on the PR, but need feedback on that before I can review.

Yup, the ball is in my court. I'll rebase it to make the git diff more readable and push it the first thing tomorrow.

Yet another Jenkins build after splitting the changes into two commits. This is mainly to ensure I didn't drop anything crucial when I kept resetting git head: https://ci.lsst.codes/blue/organizations/jenkins/stack-os-matrix/detail/stack-os-matrix/32915/pipeline

Thanks for reworking that: looking at the individual commits now made a lot more sense.