QSqlRelationalTableModel provides incorrect display data after editing a foreign cell

I've created a simplest application. It displays some persons in a table view. It reads them from sqlite database together with their location information (cities). Editing can be done using QSqlRelationalDelegate class.

After editing a foreign cell (a city of some person) I observe a value of a foreign key ("3") instead of a city's name ("USA").

I've attached screenshots and a test source code in archive to this ticket.