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

Backport of e8cf4f8abe 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/models.py

@@ -112,12 +112,13 @@ def clear_site_cache(sender, **kwargs):
     Clears the cache (if primed) each time a site is saved or deleted
     """
     instance = kwargs['instance']
+    using = kwargs['using']
     try:
         del SITE_CACHE[instance.pk]
     except KeyError:
         pass
     try:
-        del SITE_CACHE[Site.objects.get(pk=instance.pk).domain]
+        del SITE_CACHE[Site.objects.using(using).get(pk=instance.pk).domain]
     except (KeyError, Site.DoesNotExist):
         pass
 pre_save.connect(clear_site_cache, sender=Site)