I was referring back to your original a) and b) items.

Perhaps 'accidental' versus 'intentional, for whatever reason', would be the better contrast.

The weekly new issue report comes out on Fridays around noon eastern US.  I hope someone else clicks on this one.

I suggested the possibility of python-list because there would usually be people 'competing' to explain the puzzling behavior and check for obscure clauses on the reference.  In any case, some analysis would have to precede action.