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

從連結的 Python 討論開始，使用 CPython 3.10、3.11 和 3.12 在 Windows 上重現該行為。追蹤找到標準函式庫後，登錄機碼 PythonPath 如何為預設模組搜尋路徑作出貢獻；當預期行為以及任何所需的回歸涵蓋範圍都確立後，即表示完成。