The IPv4RouteParser regular expression fails to match when there is nothing after the interface name like in the following case:
$ ip route
default via 10.1.52.1 dev eth0
10.1.52.0/23 dev eth0 proto kernel scope link src 10.1.52.148
More tests needed based on iwlist output, but the side-effect-free
part of GetSupportedFrequencies() has been been broken out into a function
that can now be tested without calling core.Exec().