Merge branch 'fix-port-host-net' of https://github.com/ssanderson/docker-py into…

Merge branch 'fix-port-host-net' of https://github.com/ssanderson/docker-py into ssanderson-fix-port-host-net

docker/client.py

@@ -733,9 +733,15 @@ class Client(requests.Session):
         s_port = str(private_port)
         h_ports = None
 
-        h_ports = json_['NetworkSettings']['Ports'].get(s_port + '/udp')
+        # Port settings is None when the container is running with
+        # network_mode=host.
+        port_settings = json_['NetworkSettings']['Ports']
+        if port_settings is None:
+            return None
+
+        h_ports = port_settings.get(s_port + '/udp')
         if h_ports is None:
-            h_ports = json_['NetworkSettings']['Ports'].get(s_port + '/tcp')
+            h_ports = port_settings.get(s_port + '/tcp')
 
         return h_ports