title: Compare two branches in git from outside of the repo
body: <p>If I clone my git repository, comparing two branches is simple.</p>
  
  <pre><code>git clone $REPOURL repodir
  cd repodir
  git diff branch1..branch2
  </code></pre>
  
  <p>I'd like to be able to do this using the URL without cloning the repository.
  This would be useful for reviewing changes in someone else's repository without having to clone it first.</p>
  
  <p>I've seen various vague examples posted, but nothing worked in my git version: 2.14.1</p>
  
  <p>Reading through the git diff documentation didn't really lead me to a working example either (yet), so posting here to speed up the process of figuring out the answer.  Thanks!</p>