crash due to improper reference counting in pyside and pyqt4

segfault.py

implementation = "PySide"

if implementation == "PySide":
    from PySide.QtCore import *
    from PySide.QtGui import *
else:
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *

import sys
import random

keepalive = [ "comment out string from this list for a crash"
             #,"string"
             #,"qimage"
             #,"qpixmap"
             ]

# setting this to true will fix the bug
make_copy_save_the_day = False

# a silly 150x150 pixel gradient
def make_image():
    pixel = lambda r, g, b: chr(0) + chr(int(r * 255)) + chr(int(g * 255)) + chr(int(b * 255))
    pixels = []
    for y in range(150):
        for x in range(150):
            pixels.append(pixel(y / 150., x / 150., 0))
    return "".join(pixels)

class MyPaintedWidget(QWidget):
    references = []
    def __init__(self):
        super(MyPaintedWidget, self).__init__()

        self.t = QTimer(self)
        self.t.timeout.connect(self.set_image)
        self.t.start(100)

        self.set_image()

    def set_image(self):
        image = make_image()
        if "string" in keepalive: self.references.append(image)

        if make_copy_save_the_day:
            # this copy is made before image gets invalidated
            image = QImage(buffer(image), 150, 150, QImage.Format_RGB32).copy()
        else:
            image = QImage(buffer(image), 150, 150, QImage.Format_RGB32)
        if "qimage" in keepalive: self.references.append(image)

        self.image = QPixmap.fromImage(image)
        if "qpixmap" in keepalive: self.references.append(self.image)

        self.update()

    def paintEvent(self, event):
        qp = QPainter(self)
        qp.drawPixmap(event.rect(), self.image, event.rect())
        del qp

def main():
    app = QApplication(sys.argv)

    w = MyPaintedWidget()
    w.show()

    app.exec_()

main()