QA: Convert nodes to objects

[ganeti-local] / test / data / ip-addr-show-lo-oneline.txt

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN \    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
1: lo    inet 127.0.0.1/8 scope host lo
1: lo    inet6 ::1/128 scope host \       valid_lft forever preferred_lft forever