Check update-inetd line 29. I think that if it fails to open /dev/tty then it should fall back to /dev/null (which is used in the first place if DEBCONF_FRONTEND=noninteractive).
-- Fails to upgrade non-interactively https://launchpad.net/bugs/53049 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
