In issue28014 __getitem__() is idempotent. Multiple calls of __getitem__() return the same result and keep the OrderedDict in the same state.

> I'd be perfectly happy with making popitem implemented in terms of pop on subclasses when pop is overridden (if pop isn't overridden though, that's effectively what popitem already does).

I like this idea.

> Note: In the expiring case, the fix is still "wrong" if someone used popitem for the intended purpose (to get and delete).

Good catch! But old implementation still looks doubtful to me.