c288ace7b1
Fixes #8690 Consider the following scenario (e.g. OpenStack): platform issues a correct list of DNS servers, which includes both IPv4 and IPv6 resolvers, and configures DHCPv4 on the interface. DHCPv4 returns a set of IPv4 resolvers (as it can't return IPv6 ones), and this list completely overrides the list from the platform, wiping out the IPv6 resolvers completely. With this change, the merge process is more smart, as it tries to preserve IPv6 resolvers for example if the next layer provides no resolvers for IPv6. Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>