jQuery requests undefined url (used with phpdevshell)
<p>I'm creating an app using phpdevshell (which uses latest jQuery).</p>

<p>Now without any reason visible to me, jQuery started requesting an url ending with "undefined" which doesn't exist and causes 404.</p>

<p>It looks for this url: <a href="http://localhost/mysite/undefined" rel="nofollow">http://localhost/mysite/undefined</a></p>

<p>I've located the part of jQuery that does this (starting at line 7866):</p>

<pre><code>// Do send the request
// This may raise an exception which is actually
// handled in jQuery.ajax (so no try/catch here)
xhr.send( ( s.hasContent &amp;&amp; s.data ) || null );
</code></pre>

<p>Any idea why this happens? Thanks.</p>
