Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/usbcreator/gtk_frontend.py", line 57, in <lambda>
    self.exitbutton.connect('clicked', lambda x: self.abort())
  File "/usr/lib/python2.5/site-packages/usbcreator/gtk_frontend.py", line 76, in abort
    self.backend.shutdown()
  File "/usr/lib/python2.5/site-packages/usbcreator/backend.py", line 520, in shutdown
    if self.pipe:
AttributeError: Backend instance has no attribute 'pipe'