It would be fantastic to see this fix accompanied by a patch that adds a test that runs that primality check again. It's a check that probably doesn't need to

It would be fantastic to see this fix accompanied by a patch that adds a test that runs that primality check again. It's a check that probably doesn't need to run in CI over and over again, but boy would it be nice to have it codified so everyone reading now could reproducibly run the check if we felt the desire.