OK, thinking about this a little further, I think it's not as bad as I feared. The number of people likely to be introspecting __wrapped__ is quite small, and updating to the correct recursive code will still do the right thing in existing versions.

So long as we tell people this is coming, and get Georg to highlight it in the release notes for the corresponding 3.3.x point release, we should be able to fix the lru_cache bug without too much collateral damage.