title: option:first-child isn't selecting the same in all cases
body: <p>Why doesn't this work when a <code>select</code> has optgroups in it?</p>
  
  <p>doesn't work</p>
  
  <pre><code>$("option:first-child").attr("selected", "selected");
  </code></pre>
  
  <p>works</p>
  
  <pre><code>$("select&gt;option:first-child").attr("selected", "selected");
  </code></pre>
  
  <p>When I do <code>$("select:eq(1) option:first-child").val()</code> it appears to be getting the right <code>option</code>, but when I call <code>attr()</code> it isn't picking the right one.</p>
  
  <p>Example: <a href="http://jsfiddle.net/7J2Yb/" rel="nofollow">http://jsfiddle.net/7J2Yb/</a></p>