Fix legacy_net_info guard

The existing code assumes that `legacy_net_info` is always in legacy
mode, meaning a list of tuples which causes it to break when passed a
new-style NetworkInfo object.

Fixes bug 1164152

Change-Id: I2131d9b24045cd7531454b65d97776b11ec3ab02
(cherry picked from commit 948d1fefe6cb1e17c5567d3cf3313e13c16a3d57)
Merge "Fix legacy_net_info guard" into stable/grizzly