Geven monkey patching not being set in subprocesses

Hi,

I have a simple test file of:

from gevent.monkey import is_module_patched, saved


def test_auto():
    if not is_module_patched("threading"):
        print(saved)
        print(saved.keys())
        exit("not patched!")

When I run pytest normally with monkey patching it works:

python -m gevent.monkey --module pytest

But running with xdist it breaks:

❯ python -m gevent.monkey --module pytest -n auto
==================================================================================================================================================================== test session starts ====================================================================================================================================================================
platform linux -- Python 3.12.2, pytest-8.1.1, pluggy-1.4.0
rootdir: /home/myhome/Desktop/stream/xdist-gevent
configfile: pyproject.toml
plugins: xdist-3.5.0
12 workers [1 item]       
F                                                                                                                                                                                                                                                                                                                                                     [100%]
========================================================================================================================================================================= FAILURES ==========================================================================================================================================================================
_________________________________________________________________________________________________________________________________________________________________________ test_auto _________________________________________________________________________________________________________________________________________________________________________
[gw0] linux -- Python 3.12.2 /home/myhome/.cache/pypoetry/virtualenvs/xdist-gevent-hYN2y4Ul-py3.12/bin/python

    def test_auto():
        if not is_module_patched("threading"):
            print(saved)
            print(saved.keys())
>           exit("not patched!")

tests/test_some.py:8: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = Use exit() or Ctrl-D (i.e. EOF) to exit, code = 'not patched!'

>   ???
E   SystemExit: not patched!

<frozen _sitebuiltins>:26: SystemExit
------------------------------------------------------------------------------------------------------------------------------------------------------------------- Captured stdout call --------------------------------------------------------------------------------------------------------------------------------------------------------------------
{}
dict_keys([])
================================================================================================================================================================== short test summary info ==================================================================================================================================================================
FAILED tests/test_some.py::test_auto - SystemExit: not patched!
===================================================================================================================================================================== 1 failed in 0.88s =====================================================================================================================================================================

How can I monkey patch the workers too?

Reproduce the failure with tests/test_some.py using python -m gevent.monkey --module pytest -n auto, then inspect how pytest-xdist starts its workers and how gevent monkey patching is applied. Done means the worker process observes the expected patching behavior, with regression coverage for the shown command.