Fix check for valid cluster root

Change-Id: Id4d785977a0c0b6d176bbd15d9b2c81b46b45e97
diff --git a/tools/test/scenarios/net-topo.xml b/tools/test/scenarios/net-topo.xml
index 3f00f78..ecc54ce 100644
--- a/tools/test/scenarios/net-topo.xml
+++ b/tools/test/scenarios/net-topo.xml
@@ -38,7 +38,7 @@
         <step name="Net-Topo.Verify-Cluster0-LinkCount" requires="Net-Topo.Query-Cluster0"
               exec="test ${clusterTopo0LinkCount} == 140"/>
         <step name="Net-Topo.Verify-Cluster0-Root" requires="Net-Topo.Query-Cluster0"
-              exec="test '${clusterTopo0Root}' == 'of:000000000000000a' -o '${clusterTopo0Root}' == 'of:000000000000000c'"/>
+              exec="echo '${clusterTopo0Root}' | egrep -e 'of:000000000000000[0-9a-f]'"/>
 
         <!-- Verify the list of devices for the cluster -->
         <step name="Net-Topo.Verify-Cluster0-Devices"