that Mercurial still doesn't quite match

Mercurial's history rewriting is excellent. Do you know of `hg histedit`, `hg commit --amend`, `hg rebase`, `hg crecord --amend`?

If you're using Evolve, there's also `hg uncommit` and `hg amend`, amongst others:

https://www.youtube.com/watch?v=4OlDm3akbqg

(Demo begins around 9:10)