          return self._allowed_methods()
  
      @property
      def default_response_headers(self):
          # TODO: Only vary by accept if multiple renderers
          return {
              'Allow': ', '.join(self.allowed_methods),
              'Vary': 'Accept'
          }
  
      def http_method_not_allowed(self, request, *args, **kwargs):
 
</s> remove             'Vary': 'Accept'
 </s> add 
        headers = {
          return self._allowed_methods()
  
      @property
      def default_response_headers(self):
        headers = {
        headers = {
              'Allow': ', '.join(self.allowed_methods),
              'Vary': 'Accept'
          }
  
      def http_method_not_allowed(self, request, *args, **kwargs):
keep keep keep keep replace replace keep keep keep keep keep
 Only add 'Vary: Accept' header when there is more than one possible renderer. 
rest_framework/views.py