The pipenv-based tutorial at https://packaging.python.org/new-tutorials/installing-and-using-packages/ assumes we're going to be able to rely on a system pip installation for boostrapping purposes.

However, the current tutorial starts by introducing virtual environments, precisely because getting pip running reliably outside a virtual environment cross-platform with novice developers is a genuine pain due to the number of things that can go wrong - getting a single venv command to work, and then working inside the reconfigured shell avoids a lot of problems.

This means one of the core assumptions behind the structure of the new tutorial is wrong, and it's wrong in a way that means the current structure probably won't work :(

/cc @jonparrott