  from django.utils.cache import get_conditional_response
  from django.utils.http import http_date, parse_http_date_safe
  
  
  class ConditionalGetMiddleware(object):
      """
      Handles conditional GET operations. If the response has an ETag or
 
</s> remove                     # get_conditional_response() requires an unquoted version
                    # of the response's ETag.
                    etag=response['ETag'].strip('"'),
 </s> add                     etag=unquote_etag(response['ETag']), </s> remove                 etag=etag,
 </s> add                 etag=unquote_etag(etag),
from django.utils.http import http_date, parse_http_date_safe, unquote_etag
  from django.utils.cache import get_conditional_response
from django.utils.http import http_date, parse_http_date_safe, unquote_etag
  
  
  class ConditionalGetMiddleware(object):
      """
      Handles conditional GET operations. If the response has an ETag or
keep replace keep keep keep keep keep
 Fixed #26024 -- Fixed regression in ConditionalGetMiddleware ETag support.

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