Comment 2 for bug 1805183

First of all, dhclient remaining in place is not a bug. Systems are not switching to netplan and networkd on upgrade.

The restart caused by /etc/dhcp/dhclient-enter-hooks.d/resolved to tell systemd-resolved about new servers and search domains, and hence expected to happen (resolved does not support a reload action, hence restart). I'm not sure what the alternative would look like, maybe a bunch of busctl calls feeding that information to the running daemon via dbus?