Comment 2 for bug 1420403

The error looks like it's being emitted from quickstart/app.py in the quickstart code:
def watch(env, unit_name):
    """Start watching the given unit and the machine the unit belongs to.

    Output a human readable message each time a relevant change is found.

    The following changes are considered relevant for a healthy unit:
        - the machine is pending;
        - the unit is pending;
        - the machine is started;
        - the unit is reachable;
        - the unit is installed;
        - the unit is started.

    Stop watching and return the unit public address when the unit is started.
    Raise a ProgramExit if the API server returns an error response, or if
    either the service unit or the machine is removed or in error.
    """
    address = unit_status = machine_id = machine_status = ''
    collected_machine_changes = []
    watcher = env.watch_changes(watchers.unit_machine_changes)
    while True:
        try:
            unit_changes, machine_changes = watcher.next()
        except jujuclient.EnvError as err:
            raise ProgramExit(
                'bad API server response: {}'.format(err.message))