Octave-buildbot: Less painful Octave releases?

Since the minor Octave 5.2 release this January, I experienced that building and especially releasing Octave is still a difficult task. Even worse, due to some nasty bugs and the lack of a voluntary, skilled, and motivated release manager, the next major Octave 6.1 release got stuck for eight months now.

This is a companion discussion topic for the original entry at https://siko1056.github.io/blog/2020/08/17/octave-buildbot.html