All but the first migrations fail with PostgreSQL [patch included]

protected function _createMigrationTable()
{
    if ($this->_migrationTableCreated) {
        return true;
    }

    $this->_migrationTableCreated = true;

    try {
        $this->_connection->export->createTable($this->_migrationTableName, array('version' => array('type' => 'integer', 'size' => 11)));

        return true;
    } catch(Exception $e) {
        return false;
    }
}