Fixed #18191 -- Don't consider Accept-Language redundantly in cache key.

Thanks to choongmin for the original patch.

1 files changed, 12 insertions, 2 deletions

diff --git a/django/utils/cache.py b/django/utils/cache.py
index 0fceaa96e6..8f111592c4 100644
--- a/django/utils/cache.py
+++ b/django/utils/cache.py
@@ -236,8 +236,18 @@ def learn_cache_key(request, response, cache_timeout=None, key_prefix=None, cach
     if cache is None:
         cache = get_cache(settings.CACHE_MIDDLEWARE_ALIAS)
     if response.has_header('Vary'):
-        headerlist = ['HTTP_'+header.upper().replace('-', '_')
-                      for header in cc_delim_re.split(response['Vary'])]
+        is_accept_language_redundant = settings.USE_I18N or settings.USE_L10N
+        # If i18n or l10n are used, the generated cache key will be suffixed
+        # with the current locale. Adding the raw value of Accept-Language is
+        # redundant in that case and would result in storing the same content
+        # under multiple keys in the cache. See #18191 for details.
+        headerlist = []
+        for header in cc_delim_re.split(response['Vary']):
+            header = header.upper().replace('-', '_')
+            if header == 'ACCEPT_LANGUAGE' and is_accept_language_redundant:
+                continue
+            headerlist.append('HTTP_' + header)
+        headerlist.sort()
         cache.set(cache_key, headerlist, cache_timeout)
         return _generate_cache_key(request, request.method, headerlist, key_prefix)
     else: