BTW, are people similarly opposed to that comparisons can now raise exceptions? It's been mentioned a few times on c.l.py this week, but apparently not (yet) by people who bumped into it in practice.
but that's not a new thing in 2.1, is it?
No, but each release raises cmp exceptions in cases it didn't the release before. If we were dead serious about "no backward incompatibility ever, no way no how", I'd expect arguments just as intense about that. So I conclude we're not dead serious about that. Which is good! But in a world without absolutes, there are no killer arguments either.