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

从链接的 Python 讨论开始，使用 CPython 3.10、3.11 和 3.12 在 Windows 上重现该行为。跟踪找到标准库后，注册表键 PythonPath 如何为默认模块搜索路径作出贡献；当预期行为以及任何所需的回归覆盖范围都得到确定时，即表示完成。