def filter_tzfiles(name_list):
    """Returns a list of tuples for names that are tz data files."""
    for src_name in name_list:
        # pytz-2012j/pytz/zoneinfo/Indian/Christmas
        parts = src_name.split('/')
        if len(parts) > 3 and parts[2] == 'zoneinfo':
            dst_name = '/'.join(parts[2:])
            yield src_name, dst_name