TL 2024 cannot be installed on some Windows computers (again!)

[Karl Berry]

    TEXLIVE_PREFER_OWN=1 

I added a mention of this to https://tug.org/texlive/windows.html.

    In the TL doc, this is only mentioned about the changes for year 2019

At some point I'll also mention it in the TL manual, and on
https://tug.org/texlive/doc/install-tl.html.

    I don't know why the same is not done for xz as for tar

As I recall, Windows provides a (BSD-based) tar that often fails (don't
remember why/how), so overriding it with something that fails less often
is helpful. But Windows does not provide any xz program. If users
install something, usually they want it to be used.

    https://tex.stackexchange.com/a/489537

The real question to my mind is why the mingw xz fails.  If that's
really what's happening, that seems like a problem with mingw, not TL.
No one seems to be addressing that in that long q&a.

During setup, what TL does (on every platform) is try to run
"xz --version". If this succeeds (exit status zero), then it figures the
program works, and uses it.  If it fails, it falls back to the
TL-provided xz. Right now it is, evidently, succeeding. Running
install-tl with -v should show what's happening.

If someone could provide an additional test to discern when the mingw
(or whatever) xz won't "really" work, we could add that test and it
would automatically fall back in the presence of a problematic xz.

Thanks,
Karl