I updated my Guix installation on a Debian system to the latest
core-updates (8b9dbdf36fa89b7eb02).

After restarting the guix-daemon, anything requiring a build fails like
this:

# guix package --rollback
guix package: error: build failed: the group `guixbuild' specified in `build-users-group' does not exist

But:

# grep guixbuild /etc/group
guixbuild:x:999:guixbuilder01,guixbuilder02,guixbuilder03,guixbuilder04,guixbuilder05,guixbuilder06,guixbuilder07,guixbuilder08,guixbuilder09,guixbuilder10