title: django.db.utils.DatabaseError: ORA-12704: character set mismatch
body: <p>i faced a strange issue, trying to store a list of items (of length ~30) into database via <code>bulk_insert</code>, i get
  <code>django.db.utils.DatabaseError: ORA-12704: character set mismatch</code>
  but inserting items one by one via <code>save</code> is OK, even putting a few items into <code>bulk_insert</code> works.</p>