Sure, but I'm a git luser—and I'm sure I'm in the same boat as a lot of people in thinking of 'branches' as a named branch of code in the graph, not as a kind of floating pointer to a commit.

I never presented this as a problem. But clearly the nature of GitHub's pull request UI is sufficiently misleading (or the documentation sufficiently incomplete) to wrongly convince some smart people that pull requests can always change while you're reviewing them, and that there's nothing you can do about that. In this case, that misunderstanding caused them to ignore the entire feature. I just wanted to point out a neat trick that (probably) not many others had spotted before.

Now, in actual fact I would personally choose to use standard branch-based pull requests anyway, because you get to rebase your branch while work progresses on master. But then again I've never worked on an open-source project with so many interested parties, contributors or even regular committers.