title: Django: Better debug messages for manage.py loaddata
body: <p>I am trying to migrate a database from sqlite to postgres using <code>dumpdata</code>/<code>loaddata</code>. The problem is, if it fails, there are hardly any informations that are really usable for debugging - e.g. it just says <code>DataError: value too long for type character varying(100)</code>, so it's rather hard to tell which the afflicted data row for example is!</p>
  
  <p>Is there any easy way to improve its error logging (at least)?</p>