What do I need to do to fix "ERROR: Could not build wheels which use PEP 517 and cannot be installed directly"?

Question

I am building a library that follows standard practices when it comes to development, testing and release (using tox and pytest, setup.cfg, etc). Sometime this morning, I suddenly started getting the following error when I attempt to run my tests and I am stumped as to the root cause.

Building wheels for collected packages: python-step-series
  Building wheel for python-step-series (PEP 517): started
  Building wheel for python-step-series (PEP 517): finished with status 'done'
  Created wheel for python-step-series: filename=python_step_series-0.0.2.dev1.post1.dev0_g1f5fc90.d20211206-py3-none-any.whl size=17943 sha256=6db044ba1828101d1ecd7f27be55a42b63711d537a6ea01d4935eaa4122655ef
  Stored in directory: /home/user/.cache/pip/wheels/46/6f/be/601a51d80e3889cae97cbe8b1a98cc4be1004f1e97546d94ef
  WARNING: Built wheel for python-step-series is invalid: Metadata 1.2 mandates PEP 440 version, but '0.0.2.dev1.post1.dev0-g1f5fc90.d20211206' is not
Failed to build python-step-series
ERROR: Could not build wheels for python-step-series which use PEP 517 and cannot be installed directly

I know it has something to do with git tagging and the fact that my working tree is dirty, but how to fix this is beyond me. Until this morning, I never had an issue. Creating a new tag every time I want to run my tests (using tox) seems to band-aid this--until my working tree becomes dirty again. Regardless, this band-aid isn't efficient nor proper.

I'm using tox-conda instead of virtualenv, but each environment is reporting Pip version: 21.2.4 (python 3.7,3.8, 3.9. 3.10)

Has anyone else encountered or have knowledge of this issue and how to fix it?

Answer 1

I decided to wipe out my environment completely for a third time as well as delete pip's cache. Apparently, whatever was causing this issue lived in pip's cache or the "third time's the charm" superstition came true.