Return the split colon-delimited list from an environment variable.

    Returns an empty list if the variable didn't exist.

def get_environ_list(name, default=None):
    """Return the split colon-delimited list from an environment variable.

    Returns an empty list if the variable didn't exist.

    """
    packed = os.environ.get(name)
    if packed is not None:
        return packed.split(':')
    elif default is not None:
        return default
    else:
        return []