title: /assets 404 on javascript_include_tag
body: <p>In my view:</p>
  
  <pre><code> &lt;script src="http://code.jquery.com/jquery-1.8.3.js"&gt;&lt;/script&gt;
   &lt;script src="http://code.jquery.com/ui/1.10.0/jquery-ui.js"&gt;&lt;/script&gt;
   &lt;%= javascript_include_tag "modernizr" %&gt;
  </code></pre>
  
  <p>Inspect element:</p>
  
  <pre><code> &lt;script src="http://code.jquery.com/jquery-1.8.3.js"&gt;&lt;/script&gt;
  (ERROR IN RED):GET http://my-server.dev/assets/ 404 (Not Found)
   &lt;script src="http://code.jquery.com/ui/1.10.0/jquery-ui.js"&gt;&lt;/script&gt;
   &lt;script src="/assets/modernizr.js?body=1" type="text/javascript"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>I can use the stylesheet_link_tag without trouble.
  Why is the javascript tag getting a 404?</p>