Fixes #19919: get_language_from_request() disregards "en-us" and "en" languages

when matching Accept-Language

django/utils/translation/trans_real.py

@@ -364,10 +364,14 @@ def get_supported_language_variant(lang_code, supported=None):
     if supported is None:
         from django.conf import settings
         supported = dict(settings.LANGUAGES)
-    if lang_code and lang_code not in supported:
-        lang_code = lang_code.split('-')[0] # e.g. if fr-ca is not supported fallback to fr
-    if lang_code and lang_code in supported and check_for_language(lang_code):
-        return lang_code
+    if lang_code:
+        # e.g. if fr-CA is not supported, try fr-ca;
+        #      if that fails, fallback to fr.
+        variants = (lang_code, lang_code.lower(), lang_code.split('-')[0],
+                    lang_code.lower().split('-')[0])
+        for code in variants:
+            if code in supported and check_for_language(code):
+                return code
     raise LookupError(lang_code)
 
 def get_language_from_path(path, supported=None):
@@ -438,14 +442,13 @@ def get_language_from_request(request, check_path=False):
             # need to check again.
             return _accepted[normalized]
 
-        for lang, dirname in ((accept_lang, normalized),
-                (accept_lang.split('-')[0], normalized.split('_')[0])):
-            if lang.lower() not in supported:
-                continue
-            for path in all_locale_paths():
-                if os.path.exists(os.path.join(path, dirname, 'LC_MESSAGES', 'django.mo')):
-                    _accepted[normalized] = lang
-                    return lang
+        try:
+            accept_lang = get_supported_language_variant(accept_lang, supported)
+        except LookupError:
+            continue
+        else:
+            _accepted[normalized] = accept_lang
+            return accept_lang
 
     try:
         return get_supported_language_variant(settings.LANGUAGE_CODE, supported)

tests/i18n/tests.py

@@ -30,7 +30,8 @@ from django.utils.translation import (activate, deactivate,
     ngettext, ngettext_lazy,
     ungettext, ungettext_lazy,
     pgettext, pgettext_lazy,
-    npgettext, npgettext_lazy)
+    npgettext, npgettext_lazy,
+    check_for_language)
 
 from .commands.tests import can_run_extraction_tests, can_run_compilation_tests
 if can_run_extraction_tests:
@@ -1114,3 +1115,40 @@ class LocaleMiddlewareTests(TestCase):
         self.assertContains(response, "Oui/Non")
         response = self.client.get('/en/streaming/')
         self.assertContains(response, "Yes/No")
+
+@override_settings(
+    USE_I18N=True,
+    LANGUAGES=(
+        ('bg', 'Bulgarian'),
+        ('en-us', 'English'),
+    ),
+    MIDDLEWARE_CLASSES=(
+        'django.middleware.locale.LocaleMiddleware',
+        'django.middleware.common.CommonMiddleware',
+    ),
+)
+class CountrySpecificLanguageTests(TestCase):
+
+    urls = 'i18n.urls'
+
+    def setUp(self):
+        trans_real._accepted = {}
+        self.rf = RequestFactory()
+
+    def test_check_for_language(self):
+        self.assertTrue(check_for_language('en'))
+        self.assertTrue(check_for_language('en-us'))
+        self.assertTrue(check_for_language('en-US'))
+
+
+    def test_get_language_from_request(self):
+        r = self.rf.get('/')
+        r.COOKIES = {}
+        r.META = {'HTTP_ACCEPT_LANGUAGE': 'en-US,en;q=0.8,bg;q=0.6,ru;q=0.4'}
+        lang = get_language_from_request(r)
+        self.assertEqual('en-us', lang)
+        r = self.rf.get('/')
+        r.COOKIES = {}
+        r.META = {'HTTP_ACCEPT_LANGUAGE': 'bg-bg,en-US;q=0.8,en;q=0.6,ru;q=0.4'}
+        lang = get_language_from_request(r)
+        self.assertEqual('bg', lang)