$ ./test_lib_juju.py 
Task exception was never retrieved
future: <Task finished coro=<main() done, defined at ./test_lib_juju.py:19> exception=Exception("Couldn't authenticate to %s", 'jimm.jujucharms.com:443')>
Traceback (most recent call last):
  File "/usr/lib/python3.5/asyncio/tasks.py", line 239, in _step
    result = coro.send(None)
  File "./test_lib_juju.py", line 21, in main
    await connect_to_model_current(model)
  File "./test_lib_juju.py", line 16, in connect_to_model_current
    await model.connect_current()
  File "/usr/local/lib/python3.5/dist-packages/juju/model.py", line 391, in connect_current
    self.connection = await connection.Connection.connect_current()
  File "/usr/local/lib/python3.5/dist-packages/juju/client/connection.py", line 174, in connect_current
    '{}:{}'.format(controller_name, model_name))
  File "/usr/local/lib/python3.5/dist-packages/juju/client/connection.py", line 224, in connect_model
    endpoint, model_uuid, username, password, cacert, macaroons)
  File "/usr/local/lib/python3.5/dist-packages/juju/client/connection.py", line 161, in connect
    "Couldn't authenticate to %s", endpoint)
Exception: ("Couldn't authenticate to %s", 'jimm.jujucharms.com:443')