bug#77862: guix-daemon run as non-root sets up /etc/group incorrectly in build container

[keinflue]

Here are excerpts from the build log:

> ERROR: tests/chown/separator
> ============================
>
> ++ initial_cwd_=/tmp/guix-build-coreutils-9.1.drv-0/coreutils-9.1

[...]

> ++ id -u
> + id_u=30001
> + test -n 30001
> ++ id -un
> + id_un=nixbld
> + test -n nixbld
> ++ id -g
> + id_g=30000
> + test -n 30000
> ++ id -gn
> id: cannot find name for group ID 30000
> + id_gn=30000
> + framework_failure_
> + warn_ 'separator.sh: set-up failure: '
> + case $IFS in
> + printf '%s\n' 'separator.sh: set-up failure: '
> separator.sh: set-up failure:
> + test 9 = 2
> + printf '%s\n' 'separator.sh: set-up failure: '
> + sed 1q
> + Exit 99
> + set +e
> + exit 99
> + exit 99
> + remove_tmp_
> + __st=99
> + cleanup_
> + :
> + test '' = yes
> + cd /tmp/guix-build-coreutils-9.1.drv-0/coreutils-9.1
> + chmod -R u+rwx 
> /tmp/guix-build-coreutils-9.1.drv-0/coreutils-9.1/gt-separator.sh.Fk4W
> + rm -rf 
> /tmp/guix-build-coreutils-9.1.drv-0/coreutils-9.1/gt-separator.sh.Fk4W
> + exit 99
> ERROR tests/chown/separator.sh (exit status: 99)

[...]

> error: in phase 'check': uncaught exception:
> srfi-34 #<condition &invoke-error [program: "make" arguments: ("check" 
> "-j" "16") exit-status: 2 term-signal: #f stop-signal: #f] 2df6100> >
> phase `check' failed after 15.2 seconds
> command "make" "check" "-j" "16" failed with status 2
> build process 2 exited with status 256

Yes, I believe the patch as suggested is correct (with my limited 
understanding given that the lines above were changed in the same way).

Unfortunately I made a mistake and accidentally lost the container in 
which I tried this, so I can not verify right now whether the patch 
actually resolves the issue.

It might take me a day or two to restore it.

This happened either during or shortly after bootstrap builds, so I 
don't know whether this was the final coreutils package or one from 
commencement.scm.

Best,
keinflue