Comment 27 for bug 1575940

I've reproduced the issue and I'm working on a fix now.

It happens when deploying a node on a subnet which has DNS servers defined. Having only DNS servers (there's no way to get the search domains from MAAS 1.9 API) means we won't try to parse /etc/resolv.conf on the host to fill in the blanks while generating the container's /etc/network/interfaces.