It's not the project that asks people to push fixups, it's that GitHub, as opposed to e.g. Gerrit, makes it hard to see what changed (how your comments were add

It's not the project that asks people to push fixups, it's that GitHub, as opposed to e.g. Gerrit, makes it hard to see what changed (how your comments were addressed) after a force push, so it's best that people only add commits. Ideally they'd use git commit --fixup=<sha> -p, and then git rebase --autosquash when the maintainer approves the merge, but few people care. (And what I'm saying isn't really accurate any more since GitHub does show force-pushes in the pull request UI these days and one can run git range-diff on that. But this wasn't possible last year.)