We found two occurrences of external code breaking due to this change, and one looks tricky to fix (docutils), this indicates there are other library that will break.

> My (somewhat educated) gut feeling is that most users simply won't care or won't even notice the change.

I concur with this. Why changing the default behavior? The costs of changing this looks high, and the benefits looks very low (people not noticing).

As already proposed, a keyword-only `sorted` parameter defaulting to True (the current behavior) would allow one to give False and get control of ordering, and won't break any existing library.

On the plus side `sorted=True` makes the current behavior (sorted by default) more discoverable.