Accessing system dbus twice gives segmentation fault

Question

Dbus gives me some headache. Namely calling SystemBus() twice, will give me segmentation fault in most of the times. Sometimes it gives some other random errors so I guess this is a race condition.

from dbus.mainloop.glib import DBusGMainLoop
from time import sleep
import threading
import dbus, gobject


# Monitor usb on a separate thread
def monitor_usb():
    DBusGMainLoop(set_as_default=True)
    dbus.SystemBus()                      # Probably source of error
    gobject.threads_init()
    gobject.MainLoop().run()
thread=threading.Thread(target=monitor_usb)
thread.daemon=True
thread.start()


# Calling this while monitor_usb is running
# will cause segmentation fault
dbus.SystemBus()
sleep(10)

Is there a way to solve this?