The "Python-with-imports" case is the status quo with setup.py, and we
already know that's a pain because you need to set up an environment
that already has the right dependencies installed to enable your
module level imports in order to run the script and find out what
dependencies you need to install to let you run the script in the
first place.

The "Python-without-imports" approach would just be confusing -

So rather than saying "the bootstrapping dependency declaration file
is Python-but-not-really", it's easier to say "it's an ini-file format
that can be parsed with the configparser module" or "it's JSON" (I'm
ruling out any options that don't have a stdlib parser in Python 2.7)