QScrollBar attached to QScrollArea visibility is not updated correctly

QScrollBar attached to QScrollArea remains visible, not visually but the QScrollArea.verticalScrollBar() returns isVisible=true, even when the widget inside the scroll area is smaller than the area itself. QScrollArea should not make the scroll bars visible unless the widget hosted inside of it is bigger than the area itself. 

This seems to happen only when there is a QScrollArea inside another QScrollArea and only the visibilities of the QScrollBars of the inner scroll area are not behaving as they should.

This can be avoided by calling qwait() of any amount of time after calling the show() method of the QScrollArea, to me it seems like there is some issue with the event processing.

There is a simple project attached for reproducing.