Newer releases of systemd contain a change that removes not the part
after the first dot but the part after the last when determining the
interface name (apparently some interface names actually contain a dot).
This changes the default prefix to only contain one dot and avoids the
dots added by IPv4 addresses to create a unique interface/protocol for
each DNS server (it also replaces the `:` in IPv6 addresses with
something that might cause less conflicts).
References strongswan/strongswan#1353
Tobias Brunner
bd6014a97b