Ensure venv works with source builds when using --copies

[jkloth]

Currently a venv created with --copies or on Windows doesn't respect the sysconfig.is_python_build() property of the creating interpreter. This leads to compilation errors when attempting to build extensions in the virtual environment.

Linked PRs

• GH-92897: schedule the check_home deprecation to 3.15 #129102
• [3.13] GH-92897: schedule the check_home deprecation to 3.15 (GH-129102) #130583
• [3.12] GH-92897: schedule the check_home deprecation to 3.15 (GH-129102) #130585
• gh-92897: Doc: the check_home removal has been scheduled for 3.15 #130586
• gh-92897: document removal of check_home in Doc/whatsnew/3.15.rst #133815

[jkloth]

An example error when building psutil.

running build_ext
building 'psutil._psutil_windows' extension
creating build\temp.win-amd64-3.12
creating build\temp.win-amd64-3.12\Release
creating build\temp.win-amd64-3.12\Release\psutil
creating build\temp.win-amd64-3.12\Release\psutil\arch
creating build\temp.win-amd64-3.12\Release\psutil\arch\windows
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.30.30705\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -DPSUTIL_SIZEOF_PID_T=4 -DPSUTIL_VERSION=590 -DPSUTIL_WINDOWS=1 -D_WIN32_WINNT=0x01000 -D_AVAIL_WINVER_=0x01000 -D_CRT_SECURE_NO_WARNINGS -DPSAPI_VERSION=1 -IC:\Users\Jeremy\Source\pyperformance\include -IC:\Public\Devel\cpython\main\include -IC:\Public\Devel\cpython\main\Include -IC:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.30.30705\ATLMFC\include -IC:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.30.30705\include -IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\\include\10.0.19041.0\\shared -IC:\Program Files (x86)\Windows Kits\10\\include\10.0.19041.0\\um -IC:\Program Files (x86)\Windows Kits\10\\include\10.0.19041.0\\winrt -IC:\Program Files (x86)\Windows Kits\10\\include\10.0.19041.0\\cppwinrt /Tcpsutil/_psutil_common.c /Fobuild\temp.win-amd64-3.12\Release\psutil/_psutil_common.obj
_psutil_common.c
C:\Public\Devel\cpython\main\include\Python.h(12): fatal error C1083: Cannot open include file: 'pyconfig.h': No such file or directory
error: command 'C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.30.30705\\bin\\HostX86\\x64\\cl.exe' failed with exit code 2

After the PR, this builds without error (kinda). There is a bug in setuptools that causes an additional error. This can be worked around by setting the environment variable SETUPTOOLS_USE_DISTUTILS=no.

[vstinner]

@jkloth proposed #92899 to fix this issue.

[jkloth]

I'll add that prior to 3.8 this problem did not occur. Just that source builds on Windows are a rare thing to start with much less compiling in virtual environments from a source build so this change in behavior has gone relatively unnoticed.