title: Can git do a diff of the working copy with stash
body: <p>How can I diff my current working copy against a stash?</p>
  
  <p>My use case: my working copy already contains a subset of the changes in my <code>stash@{0}</code>, but I don't want to apply <em>all</em> the changes in <code>stash@{0}</code>. I want to do a diff to help determine which desirable changes in <code>stash@{0}</code> are still missing from my working copy.</p>