QDataWidgetMapper doesn't update ComboBox after changing

Regards this example:
http://doc.qt.io/qt-5/qtsql-sqlwidgetmapper-example.html

SQL Widget Mapper example's combobox stops updating the information on that record once it has been changed, instead cloning the most recent combobox entry when using the next/previous buttons. This occurs regardless of whether the underlying database has been correctly updated.

Specific steps to replicate:

1. Open Sql Widget Mapper Example in QtCreator, run

2. Click 'Next'. Name field should read 'Bob', Type should read 'Work'.

3. Change 'Work' to 'Other'.

4. Click 'Previous' (Alice). Click 'Next' (Bob).
Note: At this point Bob's 'Type' field shows 'Home' for me. Notably, this is Alice's 'Type', neither Bob's original 'Type' nor his recently set 'Type'.

Optional: Change other records, then Next and Previous around to watch how the comboBox stops updating it's text/index once it has been changed, instead taking the value of whichever record was displayed immediately before.

See this forum post:
https://forum.qt.io/topic/63442/sql-widget-mapper-example-weirdness

May be related to:
https://bugreports.qt.io/browse/QTBUG-23973