Disabling unwanted modules in `/etc/conf.d/net` doesn't seem to work.
Setting `modules='!dhcpcd'` to disable the spurious warning, as suggested in 760093 has no effect.
Setting `modules='!plug'` to avoid the undesired default behavior in `netifrc` has no effect, as long as `/var/run/ifplugd.*.pid` exists `netifrc` **will** stop `ifplugd` when the interface is brought down, even if `ifplugd` was manually started.
760093 --> https://bugs.gentoo.org/760093