SIGSEG while QPainter::drawPixmap with negative scaling

Am sorry to not have a sample application, but it is a bit hard to reproduce.

Am painting QPixmap (1280 x 720 - this is important), but painting it flipped:

    p->scale(1, -1);
    p->translate(0, -pixmap.height());
    p->drawPixmap(QPoint(),pixmap);

The pixmap is just default fill()-ed, and is part of an QGraphicsItem of the same size.
Now, the important part is the item itself has a parent, this parent is proportionally scaled so the image to fit in view. (This is the pixmap and its item are aways painted 1:1 and the parent handles scale).

When I resize the main window horizontally, on some magical values (around 0.256...0.275 for the parent scale) the app crashes with:

qblendfunctions_p.cpp:

    while (h--) {
        const uint *src = (const quint32 *) (srcPixels + (srcy >> 16) * sbpl);
        int srcx = basex;
        int x = 0;
        for (; x<w; ++x) {
            blender.write(&dst[x], src[srcx >> 16]); //<*** Here a SIGSEGV
            srcx += ix;
        }
        blender.flush(&dst[x]);
        dst = (quint32 *)(((uchar *) dst) + dbpl);
        srcy += iy;
    }

I also must note, this happens also if I manually setTransform() on the item, without using a parent (on 4.6), but was unable to reproduce while drawing on QWidget paintEvent and directly setting the painter.scale() values.