[$] Recent disruptive changes from Setuptools

In late March, version 78.0.1 of Setuptools - an importantPython packaging tool - was released. It was scarcely half an hour beforethe first bugreport came in, and it quickly became clear that the change was farmore disruptive than anticipated. Within only about five hours 78.0.2 waspublished to roll back the change, and multiple discussions werestarted about how to limit the damage caused by future breakingchanges. Nevertheless, many users still felt the response wasinadequate. Some previous Setuptools releases have also caused problems on a smaller but still notable scale, and hopefully the developers will be more cautious going forward. But there are also lessons here for the developers of Python package installers, ordinary Python developers and end users, and even Linux distribution maintainers.