808231733104277e1c12ad41d556f933c4893639 introduced a discrepancy between the fixed zippers and PrefixZipper and EmptyZipper 46761a0 and bdbdfdc also skipped PrefixZipper
8082317 introduced a discrepancy between the fixed zippers and PrefixZipper and EmptyZipper
46761a0 and bdbdfdc also skipped PrefixZipper