Any package requiring importlib-metadata breaks locking

The most recent version of importlib-metadata is 2.0.0. This is the version that gets resolved when any package is installed that required importlib-metadata without an upper bound. For example: flake8.

The virtualenv library requires importlib-metadata < 2.0.

When project.get_environment() is called the dependencies for virtualenv are compared to the working set resolved for the Pipfile dependencies and a VersonConflict error is raised.

This is a very frustrating error because doing pipenv lock -v gives no indication of which package requires importlib-metadata < 2.0. Also inspecting pipenv graph gives no indication either.

A temporary fix would be to pin importlib-metadata == "1.7.0" in the Pipfile.

[nicofuchsg]

With pip install -U pipenv was solved for me.

[scuerda]

The workaround of deleting the Pipfile.lock file and then re-running pipenv lock always seems to work but here is what I did for a more permanent fix.

1. Destroy local pipenv virtualenv pipenv --rm
2. Uninstall pipenv brew uninstall pipenv
3. Upgrade virtualenv pip install -U virtualenv
4. Reinstall pipenv pip install --user pipenv
5. Recreate pipenv virtualenv pipenv install

Repeat runs of pipenv lock work as expected and do not re-trigger the conflict error message.