My system does no use udev.
When installing nut, I'm getting the following error:
"scripts/hotplug/nut-usbups.hotplug does not exist"
Indeed, the faulty line refers in my case to this file and is not provided in the ebuild!
if ! has_version virtual/udev; then
einfo "Installing non-udev hotplug support"
insopts -m 755