[2.2.x] Fixed #31570 -- Corrected translation loading for apps provid…

…ing territorial language variants with different plural equations.

Regression in e3e48b0.

Thanks to Shai Berger for report, reproduce and suggested fix.

Backport of dd1ca50 from master.

django/utils/translation/trans_real.py

@@ -95,7 +95,7 @@ def update(self, trans):
                 cat.update(trans._catalog)
                 break
         else:
-            self._catalogs.insert(0, trans._catalog)
+            self._catalogs.insert(0, trans._catalog.copy())
             self._plurals.insert(0, trans.plural)
 
     def get(self, key, default=None):

docs/releases/2.2.13.txt

@@ -4,9 +4,12 @@ Django 2.2.13 release notes
 
 *Expected June 3, 2020*
 
-Django 2.2.13 fixes two security issues and a bug in 2.2.12.
+Django 2.2.13 fixes two security issues and a regression in 2.2.12.
 
 Bugfixes
 ========
 
-* ...
+* Fixed a regression in Django 2.2.12 that affected translation loading for
+  apps providing translations for territorial language variants as well as a
+  generic language, where the project has different plural equations for the
+  language (:ticket:`31570`).

tests/i18n/loading/en/LC_MESSAGES/django.po

@@ -0,0 +1,23 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2020-05-13 08:42+0000\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#: trans/tests.py:16
+msgid "local country person"
+msgstr "local country person"

tests/i18n/loading/en_AU/LC_MESSAGES/django.po

@@ -0,0 +1,23 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2020-05-13 08:42+0000\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#: trans/tests.py:16
+msgid "local country person"
+msgstr "aussie"

tests/i18n/loading/en_CA/LC_MESSAGES/django.po

@@ -0,0 +1,22 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2020-05-13 08:42+0000\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#: trans/tests.py:16
+msgid "local country person"
+msgstr "canuck"

tests/i18n/loading/en_NZ/LC_MESSAGES/django.po

@@ -0,0 +1,22 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2020-05-13 08:42+0000\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+
+#: trans/tests.py:16
+msgid "local country person"
+msgstr "kiwi"

tests/i18n/loading_app/apps.py

@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class LoadingAppConfig(AppConfig):
+    name = 'loading_app'

tests/i18n/loading_app/locale/en/LC_MESSAGES/django.po

@@ -0,0 +1,25 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
+# This file is distributed under the same license as the PACKAGE package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: PACKAGE VERSION\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2020-05-13 11:39+0300\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
+"Language-Team: LANGUAGE <LL@li.org>\n"
+"Language: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+
+#: apps.py:8
+msgid ""
+"An app with its own translation files, with one for 'en' but not the "
+"regional dialects of English"
+msgstr ""

tests/i18n/tests.py

@@ -357,6 +357,51 @@ def test_language_bidi_null(self):
             self.assertIs(get_language_bidi(), True)
 
 
+class TranslationLoadingTests(SimpleTestCase):
+    def setUp(self):
+        """Clear translation state."""
+        self._old_language = get_language()
+        self._old_translations = trans_real._translations
+        deactivate()
+        trans_real._translations = {}
+
+    def tearDown(self):
+        trans_real._translations = self._old_translations
+        activate(self._old_language)
+
+    @override_settings(
+        USE_I18N=True,
+        LANGUAGE_CODE='en',
+        LANGUAGES=[
+            ('en', 'English'),
+            ('en-ca', 'English (Canada)'),
+            ('en-nz', 'English (New Zealand)'),
+            ('en-au', 'English (Australia)'),
+        ],
+        LOCALE_PATHS=[os.path.join(here, 'loading')],
+        INSTALLED_APPS=['i18n.loading_app'],
+    )
+    def test_translation_loading(self):
+        """
+        "loading_app" does not have translations for all languages provided by
+        "loading". Catalogs are merged correctly.
+        """
+        tests = [
+            ('en', 'local country person'),
+            ('en_AU', 'aussie'),
+            ('en_NZ', 'kiwi'),
+            ('en_CA', 'canuck'),
+        ]
+        # Load all relevant translations.
+        for language, _ in tests:
+            activate(language)
+        # Catalogs are merged correctly.
+        for language, nickname in tests:
+            with self.subTest(language=language):
+                activate(language)
+                self.assertEqual(gettext('local country person'), nickname)
+
+
 class TranslationThreadSafetyTests(SimpleTestCase):
 
     def setUp(self):