The dead-simple, extremely elegant solution (starting in Python 3.4) is to make pip a namespace package in the stdlib with nothing more than a __main__.py file that installs pip; no checking if it's installed and then running it, etc, just blindly install pip. Then, if you install pip as a regular package, it takes precedence and what's in the stdlib is completely ignored (this helps with any possible staleness with the stdlib's bootstrap script vs. what's in pip, etc.). You don't even need to change the __main__.py in pip as it stands today since namespace packages only work if no regular package is found.

This also means pip3 literally becomes ``import runpy; runpy.run_module('pip')``, so that is even easier to maintain (assuming pip's bin/ stub isn't already doing that because of backwards-compatibility concerns or something with __main__.py or runpy not existing far enough back, otherwise it should =).