ChebyshevBoundedField uses "." instead of "_" as field separators in its afw table persistence. This is the old way of doing things, and unfortunately causes errors when reading in older versions of tables, becaus afw converts "." to "_" in that situation.

This shows up as a unit test failure in DM-2981 (brought over from HSC) when an older version table is read in.

It is an open question whether to fix this as part of DM-2981 (which conveniently has a test that shows the problem, though not intentionally so) or separately, in which case a new test is wanted. In the former case I'm happy to do the work so I can finish DM-2981.

Many thanks to Jim Bosch for diagnosing the problem.