On 10/04/2018 06:51 PM, Antoine Pitrou wrote:
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.
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.

Adding a note saying otherwise in the docs may pointlessly scare users away.
Possibly. But not saying anything isn't the best alternative under these circumstances.