bug#29235: 26.0.50; tar.xz broken

[Devon Sean McCullough]

> On Nov 10, 2017, at 4:37 AM, Andreas Schwab <schwab@linux-m68k.org> wrote:
> 
> On Nov 09 2017, Devon Sean McCullough <Emacs-Hacker2017@jovi.net> wrote:
> 
>> Note that MacOSX lacks xz
> 
> Not even under a different name?

Turns out xz is redundant because gunzip, gzcat and zcat all work.

                Peace
                        —Devon

P.S. Transcript follows:
$ for C in cat gzcat zcat gunzip; do echo -en "$C\t"; "$C" < bar.tar.xz | 
hexdump -C | head -1; done
cat     00000000  fd 37 7a 58 5a 00 00 04  e6 d6 b4 46 02 00 21 01  
|.7zXZ......F..!.|
gzcat   00000000  62 61 72 00 00 00 00 00  00 00 00 00 00 00 00 00  
|bar.............|
zcat    00000000  62 61 72 00 00 00 00 00  00 00 00 00 00 00 00 00  
|bar.............|
gunzip  00000000  62 61 72 00 00 00 00 00  00 00 00 00 00 00 00 00  
|bar.............|

P.P.S. Users need to list and retrieve archived files.
MacOSX bsdtar -tv and -xO provide these capabilities.
I’ve never heard of anyone saving archives from Emacs
so dired and find-file satisfy 99% of mundane user needs.
Other requirements are artifacts of a brittle implementation
which, fortunately in this particular case, is sufficient after all.