As a workaround, I noticed that setting the main ethernet interface to "auto" instead of "allow-hotplug" seems to fix the problem. By way of confirmation, on a different (virtual) machine changing the "auto" to "allow-hotplog" on the main ethernet interface causes the same problem to manifest. This is still a bit mysterious, since the messages complain about 127.0.0.1 which is of course the loopback interace, already marked "auto", and presumably up pretty early.
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