pip install fails with latest version of pip

[ebrahimebrahim]

Using the latest version of pip v23.1, it seems that pip install from this repo now fails:

# start in a venv with the required packages like catkin_pkg already installed
pip install --upgrade pip # upgrade to latest pip
pip install git+https://github.com/ros/genpy

This fails with the error

ModuleNotFoundError: No module named 'catkin_pkg'

On the other hand

# start in a venv with the required packages like catkin_pkg already installed
pip install pip==23.0.1 # use the previous version of pip
pip install git+https://github.com/ros/genpy

works.

Not sure what is going on.