Python 3.11 and above adding default module search path from the “PythonPath” registry key if the standard library was found already

Bug report

Bug description:

Please see https://discuss.python.org/t/behaviour-change-in-python-3-11-compatibility-break-or-genuine-fix/54729

There's also another issue highlited in the same module by the author, but it's not important as we can workaround by setting PYTHONNOUSERSITE as seen below.

"Including import site inadvertently enables the user site packages directory because the configuration with a ._pth file doesn’t explicitly disable it. I think it should because I can’t imagine why an embedding application would ever want that. You’ll have to set PYTHONNOUSERSITE to work around this."

CPython versions tested on:

3.10, 3.11, 3.12

Operating systems tested on:

Windows

リンクされたPythonのディスカッションから始め、CPython 3.10、3.11、3.12を使用してWindows上で動作を再現します。標準ライブラリが見つかった後、レジストリキーPythonPathがデフォルトのモジュール検索パスにどのように寄与するかを追跡します。意図された動作と、必要な回帰テストのカバレッジが確立されれば完了です。