tox4: sub process "pip list" by "subprocess.Popen, communicate()" returns empty in Fedora 36 container in GitHub Actions

[junaruga]

Issue

Describe what's the expected behaviour and what you're observing.

The tox 4.0.11 is executed in Fedora 36 and 35 Docker containers on GitHub Actions (host OS: Ubuntu 22.0.4 LTS).

The tox executes the pip list as a sub process in the following code.

https://github.com/junaruga/rpm-py-installer/blob/2e4e7fe87c17639d06386653125d942228fb306f/install.py#L1546-L1547

        cmd = '{0} list --format json'.format(self._get_pip_cmd())
        json_str = Cmd.sh_e_out(cmd).split('\n')[0]

https://github.com/junaruga/rpm-py-installer/blob/2e4e7fe87c17639d06386653125d942228fb306f/install.py#L1979-L1985

            proc = subprocess.Popen(cmd, **cmd_kwargs)
            stdout, stderr = proc.communicate()
            returncode = proc.returncode
            message_format = (
                'CMD Return Code: [{0}], Stdout: [{1}], Stderr: [{2}]'
            )
            Log.debug(message_format.format(returncode, stdout, stderr))

[DEBUG] CMD: /work/.tox/py310/bin/python -m pip list
[DEBUG] CMD Return Code: [0], Stdout: [None], Stderr: [b'']

[DEBUG] CMD: pip list
[DEBUG] CMD Return Code: [0], Stdout: [None], Stderr: [b'']

Interestingly when running the used Fedora 36 containers on local environment (Fedora 37), the pip list returned the stdout correctly. And this issue doesn't happen on the latest tox version 3 (= 3.27.1).

Environment

Provide at least:

• OS: Fedora Linux 36 and 35 Docker containers on GitHub Actions (Ubuntu 22.0.4 LTS).
• pip list of the host Python where tox is installed:

 + pip list
Package                  Version
------------------------ ----------
attrs                    22.1.0
backports.unittest-mock  1.5
cachetools               5.2.0
chardet                  5.1.0
colorama                 0.4.6
dbus-python              1.2.18
distlib                  0.3.6
distro                   1.6.0
exceptiongroup           1.0.4
filelock                 3.8.2
gpg                      1.17.0
iniconfig                1.1.1
libcomps                 0.1.18
packaging                22.0
pip                      22.3.1
platformdirs             2.6.0
pluggy                   1.0.0
pyproject_api            1.2.1
pytest                   7.2.0
pytest-helpers-namespace 2021.12.29
python-dateutil          2.8.1
rpm                      4.17.1
setuptools               65.6.3
six                      1.16.0
tomli                    2.0.1
tox                      4.0.11
virtualenv               20.17.1

Output of running tox

Provide the output of tox -rvv:

I am sorry, here is the used tox.ini. As the result is quite long. If you need it, I am happy to capture and share the log text.
https://github.com/junaruga/rpm-py-installer/blob/master/tox.ini#L2

Minimal example

If possible, provide a minimal reproducer for the issue:

I am sorry. I don't find a minimal reproducer.

Reproducing steps

I can tell how to reproduce this issue. Sorry for inconvenience.

1. Fork the repository: https://github.com/junaruga/rpm-py-installer .
2. Add an empty commit on the master branch such as git commit --allow-empty.
3. Push the branch to your forked repository.
4. This GitHub Actions are triggered by a push to any branches on the forked repository.
5. See "test-and-buiild (fedora_36 ...)" case in the GitHub Actions.
6. Click "Run the testes" - Search the line by "pip list". The actual log is like this.

If you want to test with tox 3 to compare the result, you can do like this.

diff --git a/tox-requirements.txt b/tox-requirements.txt
index 46ce3b9..e46c5b1 100644
--- a/tox-requirements.txt
+++ b/tox-requirements.txt
@@ -1,4 +1,4 @@
 pip
 setuptools
 virtualenv
-tox
+tox<4

[gaborbernat]

PR welcome, seems super edge case though 🤔

[junaruga]

If I could know what the cause is, I would be happy to send PR.

[gaborbernat]

Unable to replicate.