dhcpcd-discuss

Just for the record, I wrote this hook:

case "${reason}" in
	ROUTERADVERT)
		ip -6 neigh replace ${nd1_from} dev "${interface}" lladdr \
			$(echo ${nd1_source_address} | sed 's/../&:/g;s/:$//')
		;;
	EXPIRE6|STOP6|STOPPED)
		ip -6 neigh delete \
			$(ip -6 neigh show dev "${interface}" | \
				awk '/router PERMANENT/ { print $1 }') \
			dev "${interface}"
		;;
esac

And it works around my problem:
core01-arendal ~ # ip -6 neigh show dev enp2s0 | grep router
fe80::5e5e:abff:fe43:1ece lladdr 5c:5e:ab:43:1e:ce router PERMANENT

In case it may be useful to someone else :)

-- 
Alarig