Investigate why cibuildwheel utilized version is misaligned from pinned/installed version

[scbedd]

This was identified due to the build beginning to crash on 3/11. These test failures were not caused by any code merge, but instead a release of cibuildwheel.

We can tell that the version of cibuildwheel changed by comparing last known succeeding vs failed builds.

Before

After

The cause of the error is that cibuildwheel no longer assumes that wheel is NECESSARY to build your package. We can simply address it by adding:

[build-system]
requires = ["setuptools", "wheel", "cibuildwheel"]

However. That's just addressing the problem. The real question is why this occurred.

In this experiment build, we forced a pip freeze from the same python executable invoking cibuildwheel, and the freeze version is reporting 2.16.5, but the running version is reporting 2.17.0.

THIS is the source of the mystery. Why are we getting cibuildwheel==2.17.0 when everything we're seeing during install is 2.16.6?

Code:

In Build:

This issue tracks understanding this question.

CC @jalauzon-msft