[split] Database problem since 3.1.6

Hello, thanks for You work.
I'm use

PHP Code:

$this->dbutil->backup 


for backup DB from admin panel. After upgrade, in this a peace of code

PHP Code:

            while ($field = $query->result_id->fetch_field())
            {
                // Most versions of MySQL store timestamp as a string
                $is_int[$i] = ($field->type & MYSQLI_TYPE_TINY)
                        OR ($field->type & MYSQLI_TYPE_SHORT)
                        OR ($field->type & MYSQLI_TYPE_INT24)
                        OR ($field->type & MYSQLI_TYPE_LONG)
                        OR ($field->type & MYSQLI_TYPE_LONGLONG);

                // Create a string of field names
                $field_str .= $this->db->escape_identifiers($field->name).', ';
                $i++;
            } 


returned field type integer, but in DB table this field is varchar.

Method _backup from CI_DB_mysqli_utility class return wrong data without escape string field