title: git diff to see changes from another branch to my working copy
body: <p>I can compare the uncommitted changes from my working copy with the tip of another branch using:</p>
  
  <pre><code>git diff BRANCH
  </code></pre>
  
  <p>How do I reverse this, to see the diff in the other direction, from the tip of another branch to my working copy?</p>
  
  <p>I can compare commits in both directions using:</p>
  
  <pre><code>git diff BRANCH HEAD
  git diff HEAD BRANCH
  </code></pre>
  
  <p>But those compare <strong>committed</strong> changes in the current branch against another branch. I'm wanting to compare my <strong>uncommitted</strong> changes.</p>
  
  <p>I find this helpful when back-porting changes from a newer branch to an older branch.</p>