Steps to reproduce:
Consider the following code:

import pygtk
pygtk.require("2.0")
import gtk

class A(gtk.Dialog):
    def __init__(self, *args, **kwargs):
        print self.parent
        super(A, self).__init__(*args, **kwargs)

if __name__ == '__main__':
    A()
    gtk.main()

This causes a segmentation fault when ran (the application doesn't crash if you swap the 'print' statement with 'super').

Stack trace:
Program received signal SIGSEGV, Segmentation fault.

+ Trace 207450

Other information: