"git tar-tree" has been a thin wrapper around "git archive" since commit
fd88d9c8 (Remove upload-tar and make git-tar-tree a thin wrapper to
git-archive, 2006-09-24), which also made it print a message indicating
that git-tar-tree is deprecated.
Signed-off-by: NJohn Keeping <john@keeping.me.uk>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>