a per-machine or per-cluster (with different ways of expressing what's
part of a cluster) basis. In order for this to be effective, rc.conf
has to be reread after initdiskless is finished. Implement this by
adding a hook to etc/rc which rereads rc.conf by request. This can
also be implemented by renaming initdiskless to initdiskless.sh and
sourcing rc.conf there manually, but it was decided that, that would
be uglier than a hook in etc/rc.
Developed in concert with: gordon