Yeah, seems like dhcp3 is one more thing which has changed. customize-guest.sh has it like this:
DHCLIENT_CONF=/etc/dhcp3/dhclient.conf
Thanks for investigating and sharing the workaround!
With regards to RPM issue, resetpwd.awk has at least 5 different methods of changing password. It's full of conditional logic, so it's quite possible that in your case it goes for some branch which does not require RPM.
/Andrii