Bug report

Bug description:

Subprocess created withposix_spawn can have different environment when compared to a process created with stardardfork/exec.

The reason is thatposix_spawn usesos.environ (when no env was given), which is not affected byos.putenv andos.unsetenv. This is different fromexecv, which uses process environment (available throughenviron).

This can be easily reproduced withtest_putenv_unsetenv modified to callsubprocess.run withclose_fds=False (which makes it use theposix_spawn call):

importsubprocessimportsysimportosname="PYTHONTESTVAR"value="testvalue"code=f'import os; print(repr(os.environ.get({name!r})))'os.putenv(name,value)proc=subprocess.run([sys.executable,'-c',code],check=True,stdout=subprocess.PIPE,text=True,close_fds=False)assertproc.stdout.rstrip()==repr(value)os.unsetenv(name)proc=subprocess.run([sys.executable,'-c',code],check=True,stdout=subprocess.PIPE,text=True,close_fds=False)assertproc.stdout.rstrip()==repr(None)

I found it when I patched Python with#113118 (on Solaris, but this is pretty platform independent, I think).

CPython versions tested on:

3.9, 3.11

Operating systems tested on:

Other

Linked PRs

• gh-113119 fix environment handling in subprocess.Popen when posix_spawn is used #113120
• gh-113119: Fix the macOS framework installer build #113268