New comment by sgn on void-packages repository

https://github.com/void-linux/void-packages/pull/24754#issuecomment-690304351

Comment:
On 2020-09-10 06:48:52-0700, "Andrew J. Hesford" <notifications@github.com> wrote:
> The more I look at this, the more I see breakage when populating an
> alternate root. Won't `useradd`, `usermod` and `groupadd` always act
> on the system root? These commands provide a `--root` option that
> seems to redirect their actions in the way we want, but we aren't
> using that option now. It's also not clear from their man pages how
> well these commands get along with directory services.

Yes, it's broken.

> Ignoring `system-accounts` unless `$ROOTDIR = /` like @ericonr
> suggests is a reasonable way to avoid the worst of these issues. If
> you go that route, the hook should at least print all of the users
> and groups that should exist (along with ID numbers, if provided)
> for the package to function as expected.

Agree.

> If we really want to do this the "right" way, it's not obvious to me
> that the existence tests add value. For groups, just `groupadd
> --root ...` and catch the return code to know the difference between
> a real failure and an attempt to create a group that already exists.
> For users, just `useradd --root ...` and, if the return code
> indicates that the username already exists, try `usermod --root ...`
> instead.

Hm, I think we need `groupadd --prefix` and `useradd --prefix` instead.