DBusGMainLoop segfaults python if multi-threaded

python segfaults if DBusMainLoop is used in multiple threads; e.g.:

#!/usr/bin/python3

import dbus
import sys
import threading

from gi.repository import GLib

from dbus.mainloop.glib import DBusGMainLoop
#DBusGMainLoop(set_as_default=True)

if __name__ == "__main__":
    threading.Thread(target=GLib.MainLoop().run).start()

    for r in range(1000):
        print(".", flush=True, end="")
        dbus.SessionBus(private=True, mainloop=DBusGMainLoop())
        #dbus.SessionBus(private=True)

    print("")
    sys.exit(0)

$ ./test.py
.............Segmentation fault

It will also segfault if set_as_default is set to True, even without passing it to the SessionBus's mainloop parameter.