title: Code review of a branch in GitHub
body: <p>I need to do a code review of a whole branch in GitHub. I went to the <a href="https://github.com/rails/rails/branches" rel="noreferrer">branches page</a> and hit <a href="https://github.com/rails/rails/compare/master...3-1-stable" rel="noreferrer">compare</a>. There's a tab there, files changed, that shows exactly what I need, the diff between the two branches, master and the selected one. The problem is that it doesn't allow you to comment on code like a <a href="https://github.com/rails/rails/commit/5f6accf8cad1e7a116421a95d09fabfca254ad0b" rel="noreferrer">single diff does</a>:</p>
  
  <p><img src="https://i.stack.imgur.com/sS63F.png" alt="github code review interface"></p>
  
  <p>The blue bubble just doesn't appear on the branch diff page.</p>
  
  <p>Does anybody know how to perform a code review of a whole branch in GitHub?</p>
  
  <p>Thanks.</p>