          self.req.META['HTTP_IF_NONE_MATCH'] = self.resp['ETag'] = 'spam'
          self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
          self.assertEqual(self.resp.status_code, 304)
  
      def test_if_none_match_and_different_etag(self):
          self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
          self.resp['ETag'] = 'eggs'
          self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
          self.assertEqual(self.resp.status_code, 200)
 
</s> remove         quoted_etag = http.quote_etag(r'e\t"ag')
 </s> add         original_etag = r'e\t"ag'
        quoted_etag = http.quote_etag(original_etag) </s> remove * ...
 </s> add * Fixed a regression in ``ConditionalGetMiddleware`` causing ``If-None-Match`` checks
  to always return HTTP 200 (:ticket:`26024`).
    def test_if_none_match_and_same_etag_with_quotes(self):
        self.req.META['HTTP_IF_NONE_MATCH'] = self.resp['ETag'] = '"spam"'
        self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
        self.assertEqual(self.resp.status_code, 304)

          self.req.META['HTTP_IF_NONE_MATCH'] = self.resp['ETag'] = 'spam'
          self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
          self.assertEqual(self.resp.status_code, 304)
  
    def test_if_none_match_and_same_etag_with_quotes(self):
        self.req.META['HTTP_IF_NONE_MATCH'] = self.resp['ETag'] = '"spam"'
        self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
        self.assertEqual(self.resp.status_code, 304)

      def test_if_none_match_and_different_etag(self):
          self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
          self.resp['ETag'] = 'eggs'
          self.resp = ConditionalGetMiddleware().process_response(self.req, self.resp)
          self.assertEqual(self.resp.status_code, 200)
keep keep keep add keep keep keep keep keep
 Fixed #26024 -- Fixed regression in ConditionalGetMiddleware ETag support.

Thanks Denis Cornehl for help with the patch. 
tests/middleware/tests.py