post_upgrade() {
  if [ "$(vercmp $2 2.21.2-4)" -lt 0 ]; then
    if [ -f /var/lib/hwclock/adjtime ]; then
      mv /var/lib/hwclock/adjtime /etc/adjtime
    fi
    if [ -d /var/lib/hwclock ]; then
      rmdir /var/lib/hwclock
    fi
  fi
}