Qt5 QPainter::drawLine - aliased painting rules do not match available documentation

drawLine results with single-pixel solid pen with no antialiasing do not always follow what is described here:
http://qt-project.org/doc/qt-5.0/qtgui/coordsys.html

Namely, the following example from the docs is broken (does not match the picture):

QPainter painter(this);
painter.setPen(Qt::darkGreen);
painter.drawLine(2, 7, 6, 1);

All similar painting (diagonals lines with opposing X and Y directions) seem to be broken as well. Line end pixels do not follow the bottom-right pixel rule, but are off by 1 pixel (offset directions differ).

For example, I fail to draw a symmetric X with the following code:

painter.drawLine(10, 30, 30, 50); // good
painter.drawLine(10, 50, 30, 30); // bad: end pixels are (10,49) and (30,29)

Another example here:
http://stackoverflow.com/questions/16990326/qt5-qpainter-aliased-drawing-rules

Using Qt4CompatiblePainting solves all these issues, but I still believe that this mismatch needs to be either fixed or properly documented. I would personally prefer a fix, because I don't really see how different endpoint rules for different line directions are "sane and consistent", as the Qt5 behavior changes were described elsewhere).