Fixed #24073 -- Deactivated translations when leave_locale_alone is False

Thanks Tim Graham and Markus Holtermann for the reviews.

tests/user_commands/tests.py

@@ -2,6 +2,7 @@ import os
 
 from django.apps import apps
 from django.db import connection
+from django.conf import settings
 from django.core import management
 from django.core.management import BaseCommand, CommandError, find_commands
 from django.core.management.utils import find_command, popen_wrapper
@@ -52,7 +53,8 @@ class CommandTests(SimpleTestCase):
         out = StringIO()
         with translation.override('pl'):
             management.call_command('leave_locale_alone_false', stdout=out)
-            self.assertEqual(out.getvalue(), "en-us\n")
+            # get_language returns settings.LANGUAGE_CODE for NullTranslations instances
+            self.assertEqual(out.getvalue(), "%s\n" % settings.LANGUAGE_CODE)
 
     def test_configured_locale_preserved(self):
         # Leaves locale from settings when set to false