Segfault on accessing some attributes with multiple inheritance

Submitted by HyperHacker

Description

Created attachment 329333 Test case

Attached test case causes a segfault when accessing the attributes 'dummy', 'priv', 'qdata', or 'ref_count' of a class which inherits from Gtk.DrawingArea and is not yet initialized.

OS is Arch Linux AMD64, tested in Python 3.5.1.

Attachment 329333, "Test case":
gicrash.py