[tlu] TLU critical update still faliing

[Karl Berry]

    Uncompressing TeX Live Manager Updater  100%  Extraction failed.

When I run update-tlmgr-latest.sh on Unix (Alma 8), it works fine.
installer/xz/xz.universal-darwin is included in the self-archive.

Nothing significant has changed about u-t-l.sh in years, as far as I can
see/remember.  Although the version of makeself used to create the .sh
has changed over the years, I don't think the results are materially
different.

Maybe if you run
  sh -vx update-tlmgr-latest 
it will possible to discern why it ends with "Extraction failed".

The pipeline it runs to do the extraction can be seen at line 465, namely
  MS_dd_Progress "$0" $offset $s | eval "gzip -cd" | ( cd "$tmpdir"; UnTAR x
i.e., dump out the data that's embedded in the script, decompress,
detar. "UnTar" is a tiny shell function defined to run (with the "x"
argument) tar xf -". This is all standard Unix stuff, as we all know,
and nothing has changed about it in ages afaik.

Using the options --noexec --target /tmp/somedir I think it should simply
extract to the given dir without actually doing any update.

    "./update-tlmgr-latest.sh --nox11 -- --debug", the output is the same.

That --debug will cause our internal tl-specific runme.sh script to
output more stuff. But it's not getting to the point of running that
script. -k