[tz] broken compression in archive

[Paul Eggert]

Robert Elz wrote:
> The change from gzip to compress format was probably (I don't really remember
> why, or what) that I did not trust that new fangled gzip thing

Ironically, two weeks ago I fixed a bug where gzip mishandled some old .Z 
(compress-format) files! See:

http://git.savannah.gnu.org/cgit/gzip.git/commit/?id=79f88bd1e54d6042fbe50c212f836920fa208e56

These old file formats sure are taking a long time to die....