          quoted_etag = http.quote_etag(original_etag)
          self.assertEqual(quoted_etag, r'"e\\t\"ag"')
  
  
  class HttpDateProcessingTests(unittest.TestCase):
      def test_http_date(self):
          t = 1167616461.0
          self.assertEqual(http.http_date(t), 'Mon, 01 Jan 2007 01:54:21 GMT')
 
</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 from django.utils.http import http_date, parse_http_date_safe
 </s> add from django.utils.http import http_date, parse_http_date_safe, unquote_etag
        self.assertEqual(http.unquote_etag(quoted_etag), original_etag)
          quoted_etag = http.quote_etag(original_etag)
          self.assertEqual(quoted_etag, r'"e\\t\"ag"')
        self.assertEqual(http.unquote_etag(quoted_etag), original_etag)
  
  
  class HttpDateProcessingTests(unittest.TestCase):
      def test_http_date(self):
          t = 1167616461.0
          self.assertEqual(http.http_date(t), 'Mon, 01 Jan 2007 01:54:21 GMT')
keep add keep keep keep keep keep keep
 Fixed #26024 -- Fixed regression in ConditionalGetMiddleware ETag support.

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