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.
Apparently Travis doesn't have the ability to setup virtual ethernet
adapters turned on in the kernel, so this workaround doesn't work on
Travis.
Merge pull request #29 from seomoz/fix-fake-eth-device

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