docs: def init_original_response(self):
          """Get the original response for comparing, confirm is_cookie_necessary"""
          no_cookie_resp = None
          self.is_cookie_necessary = True
          if 'json' in self.request:
              self.request['data'] = json.dumps(self.request.pop('json')).encode(
                  self.encoding)
          r1 = self.req.request(
              retry=self.retry, timeout=self.timeout, **self.request)
          if 'headers' in self.request:
              # test is_cookie_necessary
              cookie = self.request['headers'].get('Cookie', None)
              if cookie:
                  new_request = deepcopy(self.request)
                  new_request['headers']['Cookie'] = ''
                  r2 = self.req.request(
                      retry=self.retry, timeout=self.timeout, **new_request)
                  no_cookie_resp = self.ensure_response(r2)
          resp = r1.x
          assert resp, ValueError(
              'original_response should not be failed. %s' % self.request)
          self.original_response = self.ensure_response(r1)
          self.encoding = self.encoding or resp.encoding
          if no_cookie_resp == self.original_response:
              self.ignore['headers'].append('Cookie')
              self.is_cookie_necessary = False
          return self.original_response