title: App shows up as "not synced" after convert_to_south
body: <p>I ran the convert_to_south command on my app. Everything seems to have gone fine: the migration is in south_migrationhistory table, migrate --list show the migration as applied BUT when I do syncdb, the app is still shows as "Not Synced". It suggests I migrate those (which does nothing, since there is nothing to migrate)</p>
  
  <p>Is this behaviour expected?</p>