Clear out original-to-copy mapping after creating copy so that we don't  prevent the last copy from being garbage collected.
Clear out original-to-copy mapping after creating copy so that we don't 
prevent the last copy from being garbage collected.


git-svn-id: a1a4b28b82a3276cc491891159dd9963a0a72fae@4156 542714f4-19e9-0310-aa3c-eee0fc999fb1

threerings/narya,threerings/narya,threerings/narya,threerings/narya,threerings/narya