Comment 29 for bug 1168742

The bug is still present in a new install of Xubuntu 16.04 (and presumably all the other *buntus using systemd 229), and this workaround still works:

sudo apt-get install dvd+rw-tools
echo 'KERNEL=="sr0", ACTION=="change", RUN+="/usr/local/bin/sr0_change.sh"' | sudo tee /etc/udev/rules.d/61-sr0-change.rules
cat << 'EOF' | sudo tee /usr/local/bin/sr0_change.sh
#!/bin/sh
dvd+rw-mediainfo /dev/sr0 > /dev/null
n=$?
if [ "$n" -ne '0' ];then eject /dev/sr0;fi
EOF

sudo chmod +x /usr/local/bin/sr0_change.sh
sudo reboot