'Applies policy specific updates to the given dict of md5 hashes for
the given ondisk_info.
:param hashes: a dict of md5 hashes to be updated
:param ondisk_info: a dict describing the state of ondisk files, as
returned by get_ondisk_files'

def _update_suffix_hashes(self, hashes, ondisk_info):

    if ('data_info' in ondisk_info):
        file_info = ondisk_info['data_info']
        hashes[None].update((file_info['timestamp'].internal + file_info['ext']))
