[edit: split off not to be too offtopic in the new sky-texture thread]
awesome thanks!
Works fine in Kubuntu 20.04. Thanks!
The only strange thing is that when extracting the “4b04163f235940e8bb25eb4d6ae3e06a.xz” package the result is another package without extension “4b04163f235940e8bb25eb4d6ae3e06a” and then extracting that package we finally get the files.
The original filename uploaded was blender-2.90.0-git20200522.bf18aa17cdaa-x86_64.tar.xz but Graphicall tends to mangle the filenames, keeping only the last extention, so the windows builds having .7Z are fine, but .tar.xz gets mangled to randomstuff.xz 
Oh, okay. I did not know that
if you rename the archive to have the .txz extension is it happier?
Yes, if I rename it works fine, I get the files in one step.
i’ll tweak the builder a little bit then to have that extention
By the way, I think there would be no problem if you package the files to 7z like in windows. I guess most of the linux distros support the format by default (just in case Graphicall keeps giving problems)
I went with tar.xz since I wasn’t sure if 7Z would keep the permission flags on the files, does it?
I really have no idea if 7z keep permission flags. The only thing I can say is that if I package as 7z, then when extracting the files from the package, then Blender works on my own system. I also remember downloading 7z blender files that others have shared and it worked.
About renaming and change of extension by Graphicall to .xz. This appears to be something new (perhaps a bug). I don’t remember the same thing happening to me before with other downloads.