For those who are still not able to create superuser, you can try it from appengine admin web interface. When you start your application you can see similar log:
prost@prost-VirtualBox:~/projects/website$ ./manage.py runserver
WARNING:root:The rdbms API is not available because the MySQLdb library could not be loaded.
INFO:google.appengine.tools.appengine_rpc:Server: appengine.google.com
INFO:root:Checking for updates to the SDK.
INFO:root:Running application dev~incloudscz on port 8000: http://127.0.0.1:8000
INFO:root:Admin console is available at: http://127.0.0.1:8000/_ah/admin
...
...
The last line with admin console is URL of an admin interface. You can create/view user there via "Datastore viewer" -> "Entity kind: auth_user" -> "List entities" or "Create entity" with is_superuser set to True.