The test "generates a network name and configuration" calls at the end
`process_public_network()`, which can return an empty list if the currently
executing machine has no usable network interfaces (this is typically the case
for workers that build rpm packages in OBS or Koji). This results in an
exception of type Errors::NetworkNoInterfaces to be thrown and causing this test
to fail.
This commit adds a mock of the PrepareNetworks.list_interfaces call that returns
a single entry with just the required defaults.
fe4743a22b