CI fails to install Python 3.9 on Windows

[tbirdso]

Overview

Seeing CI failures for build-windows-python-packages (9) across several ITK external modules where install-python.ps1 fails in Install Python step. See Issue 45 in HASI module. Log files are provided below where CI succeeds in PR and fails after merge.

Expected Behavior

Installing pip using C:\Python39-x64\python.exe C:\Python39-x64\lib\site-packages\setuptools\distutils_patch.py:25: UserWarning: Distutils was imported before Setuptools. This usage is discouraged and may exhibit undesirable behaviors or errors. Please use Setuptools' objects directly or at least import Setuptools first. Collecting pip ... Successfully installed pip-21.0.1 wheel-0.36.2

See example log at HASI Run 2291118755

Observed Behavior

Installing pip using C:\Python39-x64\python.exe Write-Error: This command cannot be run due to the error: The system cannot find the file specified.

See example log at HASI Run 2301754122

Reproducing

Github Actions CI is run with defaults set in ITKModuleTemplate. Install Python step is as follows:

• name: 'Install Python' run: | $pythonArch = "64" $pythonVersion = "3.${{ matrix.python-version-minor }}" iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/scikit-build/scikit-ci-addons/master/windows/install-python.ps1'))

CI is still passing for Python 3.6 and 3.7; 3.8 is cancelled prior to completion.