Problem is that it tries to to skip the username column on inserts. Possibly because it thinks it's a primary auto incrementing key or something. This is the query that gets send to PG:
Should be fixed in CVS, it uses primary|nextval(), and only falls back to unique if neither of those two is detected in the table..
in your [DB_DataObject] section of your ini file you can specify the
correct sequence, e.g.
sequence_users = users_id_seq