MAAS 2.2-rc1 refuses to deploy if all a node's interfaces are set to DHCP

[Rod Smith]

My MAAS server had previously been running MAAS 2.1.x (2.1.4, IIRC), and I've upgraded to MAAS 2.2.0-rc1. Since this upgrade, the server has refused to deploy any node on which all the network interfaces are configured to use DHCP, producing the following error message in the web UI:

Node failed to be deployed, because of the following error: {"network": ["Node has no address family in common with the server"]}

If one interface is set to "auto assign," the node will deploy and the interfaces set to use DHCP will receive IP addresses.

I'm attaching my /var/log/maas directory tree from the affected system. Here's the detailed MAAS version information:

$ dpkg -l '*maas*'|cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===============================-==================================-============-==================================================
ii maas 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all "Metal as a Service" is a physical cloud and IPAM
ii maas-cert-server 0.2.30-0~76~ubuntu16.04.1 all Ubuntu certification support files for MAAS server
ii maas-cli 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS client and command-line interface
un maas-cluster-controller <none> <none> (no description available)
ii maas-common 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS server common files
ii maas-dhcp 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS DHCP server
ii maas-dns 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS DNS server
ii maas-proxy 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS Caching Proxy
ii maas-rack-controller 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all Rack Controller for MAAS
ii maas-region-api 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all Region controller API service for MAAS
ii maas-region-controller 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all Region Controller for MAAS
un maas-region-controller-min <none> <none> (no description available)
un python-django-maas <none> <none> (no description available)
un python-maas-client <none> <none> (no description available)
un python-maas-provisioningserver <none> <none> (no description available)
ii python3-django-maas 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS server Django web framework (Python 3)
ii python3-maas-client 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS python API client (Python 3)
ii python3-maas-provisioningserver 2.2.0~rc1+bzr5922-0ubuntu2~16.04.1 all MAAS server provisioning libraries (Python 3)