What is the point, then, of making these packages optional in the first place? Shouldn't by that logic a missing dependency rather trigger a build failure unless someone enables a certain switch (e.g. ‘--without-xz’), e.g. for special-purpose distribution.I don't know. Realistically, any decent distributor of Python should include those optional modules, and I don't remember encountering a Python that doesn't has them.
Possibly. But not saying anything isn't the best alternative under these circumstances.Adding a note saying otherwise in the docs may pointlessly scare users away.