title: Django request QueryDict Errors on pop()
body: <p>Looking at dir(request.GET), I notice that pop is listed as a method.  I also believe i've popped off attributes from request in the past. </p>
  
  <p>Is that accurate?  If so, why would this fail?</p>
  
  <pre><code>request.GET.pop('key')
  </code></pre>