Linux now stops dhcpcd doing things that aren't really legal but happened
to work in 2.0. 0.0.0.0 is not a valid IP addresses. The old dhcpcd can
do bad things if something else sends packets to 0.0.0.0 (if you've ever
seen mixed dhcp and old old sun boxes with 0.0.0.0 as broadcast on a lan
you'd get the picture)
Alan