Dash lines disappear when scrolling

If I draw in a scrollable widget elements with Qt::DashLine style then when scrolling e.g down and back the dash line elements fully or partially disappear, whereas solid style lines remain visible all right.

To demonstrate the bug I have modified the Qt 'imageviewer' example. To reproduce:
1. Build and run the project.
2. Scroll down or left and back.
3. See the effect.

IMHO, the problem is in "src/gui/painting/qpaintengine_raster.cpp":
805 // ### I've seen this inverted devrect multiple places now...
806 QRectF clipRect = s->matrix.inverted().mapRect(QRectF(d->deviceRect));
807 d->dashStroker->setClipRect(clipRect);