[1.2.X] Fixed #15024 -- Ensure that choice of L10N format module used is stable given a stable setup of format modules in ll/ and ll_CC/ dirs. Thanks David Reynolds for the report and suggestions leading to the solution.

Backport of [15183] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15184 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/utils/formats.py

@@ -24,7 +24,9 @@ def iter_format_modules(lang):
             format_locations.append(settings.FORMAT_MODULE_PATH + '.%s')
             format_locations.reverse()
         locale = to_locale(lang)
-        locales = set((locale, locale.split('_')[0]))
+        locales = [locale]
+        if '_' in locale:
+            locales.append(locale.split('_')[0])
         for location in format_locations:
             for loc in locales:
                 try:

tests/regressiontests/i18n/tests.py

@@ -452,6 +452,19 @@ class FormattingTests(TestCase):
             settings.FORMAT_MODULE_PATH = old_format_module_path
             deactivate()
 
+    def test_iter_format_modules_stability(self):
+        """
+        Tests the iter_format_modules function always yields format modules in
+        a stable and correct order in presence of both base ll and ll_CC formats.
+        """
+        try:
+            old_l10n, settings.USE_L10N = settings.USE_L10N, True
+            en_format_mod = import_module('django.conf.locale.en.formats')
+            en_gb_format_mod = import_module('django.conf.locale.en_GB.formats')
+            self.assertEqual(list(iter_format_modules('en-gb')), [en_gb_format_mod, en_format_mod])
+        finally:
+            settings.USE_L10N = old_l10n
+
 
 class MiscTests(TestCase):