fix enabling dhcp on a virtual interface

examples/answers-bond.yaml

@@ -20,6 +20,10 @@ Network:
         subnet: "10.2.0.0/24"
         address: 10.2.0.1
         searchdomains: lab
+    - obj: [interface name bond10]
+      action: EDIT_IPV4
+      method-data:
+        method: dhcp
     - action: done
 Proxy:
   proxy: ""

subiquitycore/controllers/network.py

@@ -67,7 +67,8 @@ class SubiquityNetworkEventReceiver(NetworkEventReceiver):
         netdev = self.model.update_link(ifindex)
         if netdev is None:
             return
-        if not (netdev.info.flags & IFF_UP) and ifindex in self.default_routes:
+        flags = getattr(netdev.info, "flags", 0)
+        if not (flags & IFF_UP) and ifindex in self.default_routes:
             self.default_routes.remove(ifindex)
             for watcher in self.default_route_watchers:
                 watcher(self.default_routes)