[andybak]

What versions of Python didn't have this behaviour? It was there but just not guaranteed.

I don't see how anything could break (unless there are alternative implementations with different behaviour I'm not aware of?)

[masklinn]

> It was there but just not guaranteed.

Dicts have been effectively ordered since 3.6. Iteration order was literally randomised (at process start) before 3.6. I'm also not sure whether the behaviour under deletion was changed between 3.6 and 3.7 so it's possible that there are subtle differences there.