title: Override default queryset with using as_manager
body: <p>Django documents state we can override default queryset using manager's get_queryset method.</p>
  
  <p>What if I user models.Queryset and as.manager method to avoid duplicate methods. How can I override default query? </p>
  
  <p>It seems get_queryset method of models.Queryset doesnt seems to work in this case.</p>
  
  <p>Thanks.</p>