'Attempt to read a course policy from policy_path.  If the file
exists, but is invalid, log an error and return {}.
If the policy loads correctly, returns the deserialized version.'

def load_policy(self, policy_path, tracker):

    if (not os.path.exists(policy_path)):
        return {}
    try:
        with open(policy_path) as f:
            return json.load(f)
    except (IOError, ValueError) as err:
        msg = 'ERROR:    loading    courselike    policy    from    {0}'.format(policy_path)
        tracker(msg)
        log.warning(((msg + '    ') + str(err)))
    return {}
