title: p4 diff does not show newly added files
body: <p>I need some help.
  How do I get diff using p4 diff so that my patch contains
  information about newly added files too ?</p>
  
  <pre><code>p4 add foo.cc
  p4 diff &gt; my.patch
  </code></pre>
  
  <p>my.patch should contain foo.cc</p>