Changing the IP address on an interface while a dhcp server is active
on that interface, silently takes down dhcp on all interfaces, without
you noticing it, at least not until some time later, when leases start
The obvious theory is that changing the IP address renders the dhcp
config invalid, preventing dhcpd from starting. Perhaps an extra check
or warning would be appropriate. Or maybe just disabling dhcp for any
interface whose basic config changes?