bug#41201: 26.1; tar-mode-show-date prints middle-endian dates despite TIME_STYLE=long-iso

[Eli Zaretskii]

> From: trentbuck@gmail.com (Trent W. Buck)
> Date: Tue, 12 May 2020 14:40:02 +1000
> 
> Middle-endian ("US style") dates confuse me.
> I set TIME_STYLE=long-iso so I won't have to deal with them.
> This works for GNU ls and GNU tar:
> 
>     bash5$ touch x; ls -l x; tar cf x.tar x; tar tvf x.tar
>     -rw-r--r-- 1 twb twb 0 2020-05-12 14:32 x
>     -rw-r--r-- twb/twb           0 2020-05-12 14:32 x
> 
> This doesn't work for tar-mode, because
> it processes tarballs using native elisp:
> 
>     bash5$ emacs -Q -eval '(setq-default tar-mode-show-date t)' x.tar
>      -rw-r--r--     twb/twb           0 May 12 14:33 2020 x

This is already fixed in what will become Emacs 27.1: there we display
the date in the yy-mm-dd format.  You can find the latest pretest of
Emacs 27.1 on alpha.gnu.org.

Thanks.