QPainter::drawPolyline + raster paint engine creates wrong pixels

For a special sequence of points the raster paint engine draws a polyline by 1 pixel wrong.
In certain situations ( see the attached example code ), where a polyline changes its direction the line continues at the wrong position.

In the attached example it is only about a few pixels only, but with longer lines the number of wrong pixels is growing.

This bug has been introduced somewhere with Qt 4.8 - all versions <= Qt 4.7.x should be fine ( I checked Qt 4.4, 4.5. 4.6. 4.7 )