Comment 7 for bug 1463461

This works again with adding this udev rule:

$ cat /lib/udev/rules.d/70-iscsi-network-interface.rules
SUBSYSTEM=="net", ACTION=="add", RUN+="/lib/open-iscsi/net-interface-handler start"
SUBSYSTEM=="net", ACTION=="remove", RUN+="/lib/open-iscsi/net-interface-handler stop"

In my test I removed /etc/init/iscsi-network-interface.conf and /lib/systemd/system/ifup@.service.d/open-iscsi.conf as they are redundant with hotplugging. They would still be relevant if someone is supposed to ifup/ifdown the iscsi interface and expect net-interface-handler to run; if we want the latter, then we should keep the upstart job/systemd drop-in (net-interface-handler is idempotent, so running it twice doesn't matter), otherwise we can clean them up.