[1.7.x] Fixed #24332 -- Fixed contrib.sites create_default_site() when 'default' DATABASES is empty.

Backport of e8cf4f8abec87b9da6ed8e5c8cf833af9b27f4dd from master

django/contrib/sites/management.py

@@ -17,7 +17,7 @@ def create_default_site(app_config, verbosity=2, interactive=True, using=DEFAULT
     if not router.allow_migrate(using, Site):
         return
 
-    if not Site.objects.exists():
+    if not Site.objects.using(using).exists():
         # The default settings set SITE_ID = 1, and some tests in Django's test
         # suite rely on this value. However, if database sequences are reused
         # (e.g. in the test suite after flush/syncdb), it isn't guaranteed that

django/contrib/sites/tests.py

@@ -107,7 +107,7 @@ class CreateDefaultSiteTests(TestCase):
         self.assertEqual(Site.objects.count(), 1)
 
     @unittest.skipIf('other' not in connections, "Requires 'other' database connection.")
-    def test_multi_db(self):
+    def test_multi_db_with_router(self):
         """
         #16353, #16828 - The default site creation should respect db routing.
         """
@@ -121,6 +121,13 @@ class CreateDefaultSiteTests(TestCase):
         finally:
             router.routers = old_routers
 
+    @unittest.skipIf('other' not in connections, "Requires 'other' database connection.")
+    def test_multi_db(self):
+        create_default_site(self.app_config, using='default', verbosity=0)
+        create_default_site(self.app_config, using='other', verbosity=0)
+        self.assertTrue(Site.objects.using('default').exists())
+        self.assertTrue(Site.objects.using('other').exists())
+
     def test_save_another(self):
         """
         #17415 - Another site can be created right after the default one.

docs/releases/1.7.5.txt

@@ -16,3 +16,6 @@ Bugfixes
 
 * Fixed a regression that prevented custom fields inheriting from
   ``ManyToManyField`` from being recognized in migrations (:ticket:`24236`).
+
+* Fixed crash in ``contrib.sites`` migrations when a default database isn't
+  used (:ticket:`24332`).