flake8 would have caught the regression in #371 and output:
`pipenv/cli.py:257:19: F821 undefined name 'hashed_deps_path'`
Whilst in an ideal world there would be 100% test coverage, linters help
fill in the gaps, plus spot potential unused variable/imports cleanup.
I'm happy to disable more of the style/whitespace pep8 rules if
needed - the priority is having the pyflakes subset run in CI.