dhclient-script ignores "option host-name" from DHCP-server

Binary package hint: dhcp-client

I have a set of machines running Ubuntu 9.10. These computers should receive their hostnames via DHCP from a DHCP server. For each host, the "option host-name" is set on the DHCP server and the lease file in "/var/lib/dhcp3" shows me, that the hostname was received.

However, the host name won't be set, even if /etc/hostname is deleted. It works this way with Debian.

I've figured out, that it can't work, since in /sbin/dhclient-script the following code is used to set the hostname:

set_hostname() {
    local current_hostname=$(hostname)
    if [ -z "$current_hostname" -o "$current_hostname" = "(none)" ]; then
        hostname "$new_host_name"
    fi
}

If I delete /etc/hostname or keep it empty, Ubuntu sets the hostname automatically to "localhost" - therefore the upper script will fail. It now works, after changing it to:

if [ -z "$current_hostname" -o "$current_hostname" = "localhost" ]; then

Probably the way, how Ubuntu deals with a missing /etc/hostname differs from the way how Debian does...