This seems to be tied to a missing build dependency on python3-sphinx-autoapi. I added that to my chroot, and now the build for cedar-backup3 succeeds.
However, I don't think it adding to the build dependencies here is the right step. I believe that python3-sphinx-autoapi is missing the dependency. Bug #997341 for src:sphinx-autoapi shows the same problem, so I think the solution is just to add the dependency there, and then all downstream packages will build again. KEN -- Kenneth J. Pronovici <prono...@debian.org>
