Comment 2 for bug 861377

StacktraceTop:
 g_assertion_message (domain=0x0, file=0x871ebc0 "/build/buildd/pygobject-3.0.0/gi/_gobject/pygobject.c", line=929, func=0x871f44f "pygobject_new_full", message=<optimized out>) at /build/buildd/glib2.0-2.30.0/./glib/gtestutils.c:1425
 g_assertion_message_expr (domain=0x0, file=0x871ebc0 "/build/buildd/pygobject-3.0.0/gi/_gobject/pygobject.c", line=929, func=0x871f44f "pygobject_new_full", expr=0x871f181 "tp != NULL") at /build/buildd/glib2.0-2.30.0/./glib/gtestutils.c:1436
 pygobject_new_full (obj=0xa07f150, sink=1, g_class=0x0) at /build/buildd/pygobject-3.0.0/gi/_gobject/pygobject.c:929
 pygobject_new (obj=0xa07f150) at /build/buildd/pygobject-3.0.0/gi/_gobject/pygobject.c:956
 _pygi_marshal_to_py_interface_object (state=0xbfcc2804, callable_cache=0xa06d400, arg_cache=0xa0930c8, arg=0xbfcc2824) at /build/buildd/pygobject-3.0.0/gi/pygi-marshal-to-py.c:748