> With arbitrary order, it made sense to sort, so as to always give the same
> "pretty" representation. But now that order is "part of" the dict itself,
> it seems prettyprint should present the preserved order of the dict.

I disagree. Many uses of dicts are still conceptually unordered, even if
the dict now preserves insertion order. For those use-cases, insertion
order is of no interest whatsoever, and sorting is still "prettier".