canFetchMore() is called when it should not be

The documentation for canFetchMore() states:

"..If canFetchMore() returns true, QAbstractItemView will call fetchMore(). However, the fetchMore() function is only called when the model is being populated incrementally...

See:
http://doc.qt.nokia.com/qabstractitemmodel.html#canFetchMore

However, the layout() function causes fetchMore() to be called indirectly, but it should not. For example, calling setFirstColumnSpanned() triggers the layout() function which again triggers fetchMore().