I’ll say here that one of the less discussed differences between git and Mercurial is that Mercurial does not allow commited history to be changed, and git does. Git users call this a “feature,” and it leads to situations like this which are utterly impossible in Mercurial.

Git allows rewriting history by design. The kernel team uses it liberally. It is debatable whether this is a good thing, but it’s one reason I stick with Mercurial.