sysconfig.get_path('platstdlib') return paths in virtual environments (or otherwise weird)

Bug report

The sysconfig.get_path function is supposed to return he following for its first argument:

• stdlib: directory containing the standard Python library files that are not platform-specific.
• platstdlib: directory containing the standard Python library files that are platform-specific.

E.g. in the python:3.11.1 Docker container:

>>> import sysconfig
>>> sysconfig.get_path('stdlib')
'/usr/local/lib/python3.11'
>>> sysconfig.get_path('platstdlib')
'/usr/local/lib/python3.11'

Or on a Python build configured with lib64 platlibdir (e.g. on Fedora Linux with $RPM_BUILD_ROOT environment variable set):

>>> import sysconfig
>>> sysconfig.get_path('stdlib')
'/usr/lib64/python3.11'
>>> sysconfig.get_path('platstdlib')
'/usr/lib64/python3.11'

Yet in virtual environments, the platstdlib directory returns a directory from within the virtual environment. E.g. in the python:3.11.1 Docker container:

>>> import sysconfig
>>> sysconfig.get_path('stdlib')
'/usr/local/lib/python3.11'
>>> sysconfig.get_path('platstdlib')
'.../myvenv/lib/python3.11'

Or on Fedora Linux:

>>> import sysconfig
>>> sysconfig.get_path('stdlib')
'/usr/lib64/python3.11'
>>> sysconfig.get_path('platstdlib')
'.../myvenv/lib64/python3.11'

This even confuses the default values on Fedora Linux (without $RPM_BUILD_ROOT environment variable set):

>>> import sysconfig
>>> sysconfig.get_path('stdlib')
'/usr/lib64/python3.11'
>>> sysconfig.get_path('platstdlib')
'/usr/local/lib64/python3.11'

I believe that here:

https://github.com/python/cpython/blob/62251c3da06eb4662502295697f39730565b1717/Lib/sysconfig.py#L30

The {platbase} variable should be replaced with {insatlled_base} or even (currently AFAIK nonexistent) {insatlled_platbase}.

Your environment

• CPython versions tested on: 3.11.1
• Operating system and architecture: Fedora Linux 37 x86_64, python:3.11.1 Docker container.

从 Lib/sysconfig.py 第 30 行附近开始，在虚拟环境、Python 3.11.1 Docker 镜像和 Fedora Linux 中复现报告的 sysconfig.get_path('stdlib') 和 get_path('platstdlib') 结果。完成的标准是：这些环境中的平台特定标准库路径与文档所述的区别一致，并在现有测试套件处理 sysconfig 路径的地方添加回归测试覆盖。