Wow, nothing here is simple. :-( Even though the examples show that there's obviously a bug, I would caution against fixing it rashly without understanding how the current behavior may be useful in other circumstances. I've lost what I recall from reading PEP 558 so I can't quite fathom the new design, but I wish you good luck trying to implement it, and hopefully it will work out as hoped for (simpler, solving the issue, keeping the useful behaviors).