> For example, if a contributor force pushes a new commit to a PR > branch, as a reviewer, I can't see the old version and compare > against it. This i

> For example, if a contributor force pushes a new commit to a PR > branch, as a reviewer, I can't see the old version and compare > against it. This is not fully true. While you can't "git fetch" that branch anymore, you can see comments against those old diffs in the pull request UI, which are the things likely to have changed. For example, I submitted this PR against uWSGI a few months ago: https://github.com/unbit/uwsgi/pull/1392 https://github.com/unbit/uwsgi/pull/1392 Initially I screwed it up and inserted a field in the middle of a struct, whereas within a stable release it should of course be added to the end. If you click on "show outdated" you can see that old diff where I'm adding the field to the middle of the struct, but click on "files changed" and it's the current change where I fixed the issue. I do think GitHub could improve here, they could expose forced pushes via refs/pull/NUM-COUNTER instead of just refs/pull/NUM as they do now, but it's important to point out that they're handling the common case. When someone force-pushes a pull request they're usually doing so in response to comments on the request, and those comments will still make sense because GitHub saves away the old diff, which you can compare with the current state.