Code review comment for lp:~raharper/curtin/trunk.passthrough-netconfig

Thanks for the review, will update with ACK'ed fixes. I think the items that remain for discussion:

1) parsing shebang for which python interpreter to use for cloud-init in-target
2) side-effect = (Exception) which it appears there was some confusion with the assert_not_called (which I agree need to be replaced with call_count checks).