QCombobox leaks memory

QCombobox leaks memory whenever (at least two) combo boxes get their content updated.

Very simple test scenario (the attached files contain this sample project):

1. Start a standard QWidgets project in QtCreator
2. Add two combo boxes to the main window (via Designer inside QCreator)
3. Add a timer to the MainWindow class that fires quickly and periodically, e.g. once per millisecond; connect its timeout signal to a MainWindow class's slot method, e.g. MainWindow::OnTimeout()
4. In this OnTimeout() method implement for each combo box: a) clear its content, b) add one or more items
   [To speed up the process these two steps per combo box could even be executed several times within a loop]
5. Build and run the program
6. Check Windows Task Manager to see how memory consumption increases

Not sure but this bug might be related to QTBUG-42446