Noticed by valgrind during test t0000.35 “writing this tree without
--missing-ok”.
Even in the cherry-pick foo..bar code path, such an error is the
end of the line. But maybe some day an interactive porcelain will
want to link to libgit, making this matter.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>