These reads as far too draconian for my tastes. I *really* don't want to give the impression that no one should submit a PR unless they're 100% confident they've met all the criteria. Instead, this checklist should just be framed as the criteria used to *merge* a pull request, and a memory aid for both the submitter and the reviewer.

For instance, it would be harmful if someone wasted time ensuring complete PEP 8, documentation and test coverage if there were considerable doubt over the structure of the code. But *knowing* that those criteria needed to be satisfied the submitter could annotate their PR to make it clear what aspect(s) of the code need attention.