MAAS subnets API returns no name servers for MAAS managed networks

Looking here:
https://maas.ubuntu.com/docs/api.html#subnet

There appears to be a place for dns_servers to be returned. Presumably one can configure a subnet with explicit name servers. However, if the subnet is managed by MAAS (such that MAAS knows it is running DHCP and DNS for that subnet), shouldn't it just add itself to the list of name servers?

In Juju we are working around this for containers by looking at the host machines /etc/resolv.conf instead of asking MAAS what the name servers should be for a given network interface. But it feels like MAAS should be the authoritative place to get that information. (How does it decide what name server to give the machine for its own configuration?)

This seems to affect both MAAS 1.8 and 1.9

See also bug #1528217 where we're having Juju work around this for containers.