[CORD-2603]
Define headnode so that interface-config can differentiate nodes

Change-Id: Iaacefc459f7c51da55326951ffb56ce68667251c
diff --git a/scenarios/single/config.yml b/scenarios/single/config.yml
index a1a144f..85393d2 100644
--- a/scenarios/single/config.yml
+++ b/scenarios/single/config.yml
@@ -30,6 +30,9 @@
 head_vm_cpu: 8
 head_vm_ip: "192.168.46.100"
 
+buildnode: head1
+headnode: head1
+
 physical_node_list:
   - name: head1
     ipv4_last_octet: 1