fix backward-search in read-line
fix backward-search in read-line

Ignore-this: f62a012bbf026b1698dd368c228aea3b

darcs-hash:20100113135715-c41ad-c9b638fbaccee2349833cf24110012194d7e1d3b.gz

avsm/lwt-OLD,avsm/lwt-OLD