[1.7.x] Fixed #22770 -- Removed create_superuser from post_migrate signals.

Moved logic to syncdb command for backwards compatibility.

Backport of 93d05536fd from master

django/core/management/commands/syncdb.py

@@ -1,10 +1,13 @@
 import warnings
 from optparse import make_option
 
+from django.apps import apps
+from django.contrib.auth import get_user_model
 from django.db import DEFAULT_DB_ALIAS
 from django.core.management import call_command
 from django.core.management.base import NoArgsCommand
 from django.utils.deprecation import RemovedInDjango19Warning
+from django.utils.six.moves import input
 
 
 class Command(NoArgsCommand):
@@ -22,3 +25,23 @@ class Command(NoArgsCommand):
     def handle_noargs(self, **options):
         warnings.warn("The syncdb command will be removed in Django 1.9", RemovedInDjango19Warning)
         call_command("migrate", **options)
+
+        try:
+            apps.get_model('auth', 'Permission')
+        except LookupError:
+            return
+
+        UserModel = get_user_model()
+
+        if not UserModel._default_manager.exists() and options.get('interactive'):
+            msg = ("\nYou have installed Django's auth system, and "
+                "don't have any superusers defined.\nWould you like to create one "
+                "now? (yes/no): ")
+            confirm = input(msg)
+            while 1:
+                if confirm not in ('yes', 'no'):
+                    confirm = input('Please enter either "yes" or "no": ')
+                    continue
+                if confirm == 'yes':
+                    call_command("createsuperuser", interactive=True, database=options['database'])
+                break