It does state on the page that when you login with GitHub "..., you temporarily grant us access to your public repositories. However, we do not store your autho

It does state on the page that when you login with GitHub "..., you temporarily grant us access to your public repositories. However, we do not store your authorization tokens on the server side, and instead use a cookie on your browser. To log out, you simply delete the cookie" The next paragraph explains why. Essentially, Github issues are being used to track and deal with reviewers' comments.