Comment 16 for bug 1377005

Jeroen,
  The 'route info' bug is a bug in cloud-init, but isnt fatal. its just cloud-init failing to parse 'route' output as you dont have ipv4 routes that it is expecting.
  The fact that ipv6 networking does not come up automatically on a device if ipv4 config is not provided is not provided is not cloud-init specific. It really feels to me that this is somehow racey as I've now reproduced that if I just *move* the 'iface eth0 inet static' to below the inet6 , that it will fail, but above it makes it pass.

Ie, this is broken:
auto eth0
iface eth0 inet6 static
  netmask 64
  address 2001:db8::1:3
  dad-attempts 0
iface eth0 inet static
  netmask 255.255.255.255
  address 127.0.254.1

but moving that inet static above works fine.