tox4 missing colour for pytest output

[hugovk]

When submitting a bug make sure you can reproduce it via tox -rvv and attach the output of that to the bug. Ideally, you should also submit a project that allows easily reproducing the bug. Thanks!

Set up

$ python --version
Python 3.11.0
$ git clone https://github.com/hugovk/tinytext
...
$ cd tinytext

tox3 behaviour

$ pip install -U tox
...
$ tox --version
tox --version
3.27.1 imported from /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/tox/__init__.py
$ tox -e py311

pytest output is in colour:

tox4 behaviour

$ pip install -U tox --pre
...
$ tox --version
4.0.0b3 from /Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/tox/__init__.py
$ tox -e py311

pytest output is no longer in colour:

[hugovk]

isatty

If I run this inside tox:

{envpython} -c "import sys; print(sys.stdout.isatty())"

I get True for tox3 and False for tox4.

And... this is a duplicate of #1773.

Sorry for the noise!