sudo system-image-cli --list-channels -v
[systemimage] Oct 23 11:33:54 2015 (4374) Looking for blacklist: https://system-image.ubuntu.com/gpg/blacklist.tar.xz
[systemimage] Oct 23 11:33:54 2015 (4374) [0xb5dfe7b0] Requesting group download:
	https://system-image.ubuntu.com/gpg/blacklist.tar.xz -> /var/lib/system-image/keyring.tar.xz
	https://system-image.ubuntu.com/gpg/blacklist.tar.xz.asc -> /var/lib/system-image/keyring.tar.xz.asc

[systemimage] Oct 23 11:33:54 2015 (4374) system-image-cli exception
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/systemimage/main.py", line 264, in main
    state.run_thru('get_channel')
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 151, in run_thru
    step()
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 215, in _get_blacklist_1
    get_keyring('blacklist', url, 'image-master')
  File "/usr/lib/python3/dist-packages/systemimage/keyring.py", line 107, in get_keyring
    (ascxz_src, ascxz_dst),
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 277, in get_files
    reactor = DownloadReactor(bus, self.callback, pausable)
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 102, in __init__
    self.react_to('canceled')
  File "/usr/lib/python3/dist-packages/systemimage/reactor.py", line 83, in react_to
    path_keyword='path')
  File "/usr/lib/python3/dist-packages/dbus/bus.py", line 148, in add_signal_receiver
    path, **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 400, in add_signal_receiver
    self._require_main_loop()
RuntimeError: To make asynchronous calls, receive signals or export objects, D-Bus connections must be attached to a main loop by passing mainloop=... to the constructor or calling dbus.set_default_main_loop(...)