Pip development install does not recognize --user flag

[Jul3k]

I am running the following command to install voila-vuetify in development mode (-e) of a local clone of the repository on a linux machine:

pip install --user -e .

This however fails because setup.py is trying to write into /usr/share/jupyter without root permission. With a print command added behind the line that checks for the --user flag,

if '--user' in sys.prefix:  # TODO: is there a better way to find out?

I found out that this expression fails to correctly detect the --user flag. The user_dirfunction contains two more errors as the env and home variable are not defined.