title: git stable branch: find not cherry-picked commits
body: <p>I have the following git history:</p>
  
  <pre><code>A --- B --- C --- D' --- E' [master]
   \
    \ --- D --- E --- F [stable]
  </code></pre>
  
  <p>We have a policy to cherry-pick all changes from stable to master; D' and E' are cherry-picked commits from stable branch, F is not cherry-picked (has been forgotten).</p>
  
  <p>How can I get a diff that bings up F (which was not cherry-picked into master)?</p>
  
  <hr>
  
  <p>We don't want use merge because:</p>
  
  <ul>
  <li>cleaner history without merge commits</li>
  <li>commits to stable are rare</li>
  <li>we have lots of different stable branches</li>
  </ul>