Comment 2 for bug 1420601

It's relatively unlikely that the initrd is related to this. The most likely change from -6 was this:

  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/commit/?id=c90467c1b29

In a boot with the failed networking, can you please run

  sudo systemctl status -u network-pre.target networking.service network.target <email address hidden>
  sudo systemctl --all | grep ifup

and copy&paste the output here? (You might first need to copy it into a file, then reboot with networking (e. g. under upstart), and then attach the file here. Thanks!