[arch-general] How to build package in "clean chroot" using the "-U" parameter?

[Manuel Reimer]

On 12/22/2017 02:26 PM, Eli Schwartz via arch-general wrote:
> AFAIK this should work fine, for its intended goal. Though I don't think
> it gets a lot of testing.

Question is: What is the intended goal. I guess it is not what I want to do?

> makechrootpkg elevates to root if needed, using sudo.

... which doesn't help me.

My autobuild process runs as root. It also directly updates the chroot 
which also needs root permissions so it's the best to start with "root" 
and then drop privileges for the tasks that shouldn't run with root 
privileges. The whole system is a dedicated build VM, so there is no 
reason to not use "root" for the main purpose of this machine.

> It then has to run
> makepkg to update sources, *before* entering the chroot for building.

That seems to be the one that works for me.

> That is the first time the makepkg command is run. The second time, is
> inside the chroot, which should automatically be run as the "builduser"
> user inside a systemd-nspawn container (we don't actually use chroot).

And this one fails. But why? Does makechrootpkg for some reason miss to 
drop privileges if the "-U" parameter is used?

Manuel