From 2cbb095bec757b804e8b6d9d0930ef3c6446a591 Mon Sep 17 00:00:00 2001
From: Claude Paroz <claude@2xlibre.net>
Date: Sat, 20 May 2017 13:28:20 +0200
Subject: [PATCH] Fixed #28221 -- Fixed plural fallback translations in
 JavaScriptCatalog view

Thanks Waldemar Kornewald for the report and initial patch.
---
 django/views/i18n.py                |  4 +++-
 tests/view_tests/tests/test_i18n.py | 18 ++++++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/django/views/i18n.py b/django/views/i18n.py
index 0b510019d5b..71f8cd575ef 100644
--- a/django/views/i18n.py
+++ b/django/views/i18n.py
@@ -273,8 +273,9 @@ class JavaScriptCatalog(View):
         catalog = {}
         trans_cat = self.translation._catalog
         trans_fallback_cat = self.translation._fallback._catalog if self.translation._fallback else {}
+        seen_keys = set()
         for key, value in itertools.chain(iter(trans_cat.items()), iter(trans_fallback_cat.items())):
-            if key == '' or key in catalog:
+            if key == '' or key in seen_keys:
                 continue
             if isinstance(key, str):
                 catalog[key] = value
@@ -283,6 +284,7 @@ class JavaScriptCatalog(View):
                 pdict.setdefault(msgid, {})[cnt] = value
             else:
                 raise TypeError(key)
+            seen_keys.add(key)
         for k, v in pdict.items():
             catalog[k] = [v.get(i, '') for i in range(num_plurals)]
         return catalog
diff --git a/tests/view_tests/tests/test_i18n.py b/tests/view_tests/tests/test_i18n.py
index 2c12177a598..8cd63765077 100644
--- a/tests/view_tests/tests/test_i18n.py
+++ b/tests/view_tests/tests/test_i18n.py
@@ -272,13 +272,27 @@ class I18NViewTests(SimpleTestCase):
     def test_i18n_fallback_language_plural(self):
         """
         The fallback to a language with less plural forms maintains the real
-        language's number of plural forms.
+        language's number of plural forms and correct translations.
         """
         with self.settings(LANGUAGE_CODE='pt'), override('ru'):
             response = self.client.get('/jsi18n/')
             self.assertEqual(
                 response.context['catalog']['{count} plural3'],
-                ['{count} plural3', '{count} plural3s', '{count} plural3 p3t']
+                ['{count} plural3 p3', '{count} plural3 p3s', '{count} plural3 p3t']
+            )
+            self.assertEqual(
+                response.context['catalog']['{count} plural2'],
+                ['{count} plural2', '{count} plural2s', '']
+            )
+        with self.settings(LANGUAGE_CODE='ru'), override('pt'):
+            response = self.client.get('/jsi18n/')
+            self.assertEqual(
+                response.context['catalog']['{count} plural3'],
+                ['{count} plural3', '{count} plural3s']
+            )
+            self.assertEqual(
+                response.context['catalog']['{count} plural2'],
+                ['{count} plural2', '{count} plural2s']
             )
 
     def test_i18n_english_variant(self):