On a fresh install on macOS (python3.8 through pyenv):
python3 -m venv ~/venvs/planemo-test
source ~/venvs/planemo-test/bin/activate
pip install planemo
planemo serve
I get an error:
Traceback (most recent call last):
File "/Users/pmoreno/.planemo/gx_venv_3/bin/pip", line 5, in <module>
from pip._internal.cli.main import main
ModuleNotFoundError: No module named 'pip._internal.cli.main'
I deleted ~/.planemo at the start of the process. @mvdbeek suggested to create before hand ~/.planemo/gx_venv_3 without virtualenv like this:
python3 -m venv ~/.planemo/gx_venv_3
which did the trick.