uci compile two different config options for unbound zone clause based on provided string value for list server.
If port is provided using '@' charactes it assumes it's a host rather than address and compile option to ' forward-host'.
It should be allow to use '@' character in addition to IP address and compile option to 'forward-addr'.
list zone_name 'myzone.loc.'
list server '10.1.0.2'
list server '10.1.0.1'