Due to the use of strncpy without explicit NUL termination,
we could end up passing names n1 or n2 that are not NUL-terminated
to queue_diff, which requires NUL-terminated strings.
Ensure that each is NUL terminated.
Signed-off-by: Jim Meyering <meyering@redhat.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>