TL 2023 update-tlmgr-latest.sh under Docker fails

[Karl Berry]

Hi Julien - regarding the upgrade failure:

    ./runme.sh: updating /opt/texlive/texdir/bin/default ...
    tar: default: Cannot stat: No such file or directory

It seems your installation has the bin dir named, literally, "default":
  /opt/texlive/texdir/bin/default
Is that right? Our little upgrade script cannot guess what that really is.
It assumes the bin/ directories are known TL platform names, like
x86_64-linux. Admittedly the error message should be improved.

    Worth noting: within the image (an Alpine Linux), TeXLive is located at
    /opt/texlive. I haven't tried to move to /usr/local/texlive/2023/and
    updating PATH. Would that help?

No. The runme.sh script runs kpsewhich --var-value=SELFAUTOPARENT to
determine the root of the installed TL tree. We can see from the path
above that it found /opt/texlive ... --best, karl.