Comment 8 for bug 1577001

@martin: I'm on desktop, fwiw. I think you nailed it:

apt-cache policy lxd systemd
# lxd:
# Candidate: 2.0.0-0ubuntu4
# systemd:
# Installed: 229-4ubuntu4

# Clean initial conditions
sudo apt purge -y lxd || true
sudo systemctl stop lxd.socket || true
sudo rm -f /var/lib/lxd/unix.socket

echo "Demonstrate proper functioning on first install"
sudo apt install -y lxd
ls -l /var/lib/lxd/unix.socket
# srw-rw---- 1 root lxd 0 May 2 10:10 /var/lib/lxd/unix.socket

echo "Purge (bug: leaves lxd.socket running, leaves unix.socket present!)"
sudo apt purge -y lxd
ls -l /var/lib/lxd/unix.socket
# srw-rw---- 1 root lxd 0 May 2 10:10 /var/lib/lxd/unix.socket

echo "Reinstall (bug: breaks group ownership of unix.socket!)"
sudo apt install -y lxd
ls -l /var/lib/lxd/unix.socket
# srw-rw---- 1 root root 0 May 2 10:10 /var/lib/lxd/unix.socket