little glitch with trying to use update-tlmgr-latest in a darwinlegacy context

[jfbu]

Hi,

For various reasons, I converted my existing 2020 into
a rolling TeXLive with current 2021 pretest.

I seem to have succeeded but encountered a problem.

sh update-tlmgr-latest.sh -- --upgrade

Verifying archive integrity... All good.
Uncompressing TeX Live Manager Updater  100%  
./runme.sh: updating in /usr/local/texlive/2020...
./runme.sh: tlmgr version says this is TeX Live 2020,
./runme.sh: and this updater script created: Tue Mar  2 02:25:21 CET 2021.
./runme.sh: ok, doing full release upgrade  from 2020 to 2021.
./runme.sh: updating /usr/local/texlive/2020/bin/x86_64-apple-darwin13.4.0 ...
tar: x86_64-apple-darwin13.4.0 : stat impossible: No such file or directory
tar: Arrêt avec code d'échec à cause des erreurs précédentes
./runme.sh: no xz.[x86_64-apple-darwin13.4.0][.exe] binary for /usr/local/texlive/2020/bin/x86_64-apple-darwin13.4.0 in /var/folders/np/4_9pppfs54xdv9m79m7rwx4w0000gn/T/selfgz37288917/installer/xz.


Turns out that in 

/usr/local/texlive/2020/tlpkg/installer/xz

there is only a  xz.x86_64-darwinlegacy indeed (actually the file date is March 2, 2019)

and I don't know if this is relevant.

I am using indeed a darwinlegacy install.

To be completely honest, but I don't know if relevant

/usr/local/texlive/2020/bin/

contains to sub-directories

x86_64-darwinlegacy

and

x86_64-apple-darwin13.4.0

(which comes from me building my own binaries in March 2020)

However my PATH only contains /Library/TeX/texbin

where texbin is a symlink which, at the time the above happened
I had been careful to let resolve to the 
/usr/local/texlive/2020/bin/x86_64-darwinlegacy
so I feel the above rather relates to some hard-coded context
in update-tlmgr-latest.sh

Was the above error expected on a TL2020 darwinlegacy ?

Anyway, I then set the repository to a pretest mirror and then 
ran

tlmgr update --self --all

and the binaries were updated to 2021 pretest. And it used
the darwinlegacy ones.

Best