When objectname:short was introduced, it forgot to copy the result of
find_unique_abbrev. Because the result of find_unique_abbrev is a
pointer to static buffer, this resulted in the same value being
substituted in for each ref.
Signed-off-by: Jay Soffian <jaysoffian@gmail.com> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>