If you look closely in the build logs, the eth0.1 setup is failing

with the following error message:

Cannot find device "eth0.1"
Failed to bring up eth0.1.

Adding the additional `ip link add` command made it work on my
machine.

We'll see if Travis likes the same fix. I'm not sure this really matters as the build doesn't seem to fail even without the eth0.1 hack.