This was found while testing PR #1022.
The build on Windows was broken.
At the end of the build was the following:
Running from numpy source directory.
C:\Users\Dave\AppData\Local\Temp\easy_install-2xqry4y_\numpy-1.23.0\setup.py:86: DeprecationWarning:
numpy.distutils is deprecated since NumPy 1.23.0, as a result
of the deprecation of distutils itself. It will be removed for
Python >= 3.12. For older Python versions it will remain present.
It is recommended to use setuptools < 60.0 for those Python versions.
For more details, see:
https://numpy.org/devdocs/reference/distutils_status_migration.html
import numpy.distutils.command.sdist
error: Cython needs to be installed in Python as a module
=============
It dies at this point.