title: page_number is always 1 in paginate_queryset in PageNumberPagination
body: <p>My view is as follows:</p>
  
  <pre><code>class ApplicationApplicantsViewSet(viewsets.ModelViewSet):
      queryset = Applicant.objects.all()
      serializer_class = ApplicantSerializer
  
      def list(self, request, application_pk=None):
          queryset = self.queryset.filter(application__pk=application_pk)
          page = self.paginate_queryset(queryset)
  
  
          if page is not None:
              serializer = self.get_serializer(page, many=True)
              return self.get_paginated_response(serializer.data)
  
          serializer = self.get_serializer(queryset, many=True)
          return Response(serializer.data)
  </code></pre>
  
  <p>Following is the paginate_queryset method</p>
  
  <pre><code> def paginate_queryset(self, queryset, request, view=None):
      """
      Paginate a queryset if required, either returning a
      page object, or `None` if pagination is not configured for this view.
      """
      self._handle_backwards_compat(view)
  
      page_size = self.get_page_size(request)
      if not page_size:
          return None
  
      paginator = DjangoPaginator(queryset, page_size)
      page_number = request.query_params.get(self.page_query_param, 1)
      if page_number in self.last_page_strings:
          page_number = paginator.num_pages
  
      try:
          self.page = paginator.page(page_number)
      except InvalidPage as exc:
          msg = self.invalid_page_message.format(
              page_number=page_number, message=six.text_type(exc)
          )
          raise NotFound(msg)
  
      if paginator.num_pages &gt; 1 and self.template is not None:
          # The browsable API should display pagination controls.
          self.display_page_controls = True
  
      self.request = request
      return list(self.page)
  </code></pre>
  
  <p>But on accessing the url with </p>
  
  <blockquote>
    <p><a href="http://url?page=2" rel="nofollow">http://url?page=2</a></p>
  </blockquote>
  
  <p>the page_number variable in paginate_queryset in PageNumberPagination is 1. Any idea why this is happening?</p>