[CORD-2554] enhance graph traversal functions and change branch conditions for playbook

Change-Id: I3d8c15f1da9485a936f8d2a94a387e95b00bd3eb
diff --git a/xos/synchronizer/steps/vspgwutenant_playbook.yaml b/xos/synchronizer/steps/vspgwutenant_playbook.yaml
index f04a5b4..e6f95c5 100644
--- a/xos/synchronizer/steps/vspgwutenant_playbook.yaml
+++ b/xos/synchronizer/steps/vspgwutenant_playbook.yaml
@@ -39,9 +39,9 @@
     - cord_version: {{ cord_version }}
 
   roles:
-    - { role: interface_config_4_1, when: cord_version == "4.1" }
-    - { role: build_and_run_4_1, when: cord_version == "4.1" }
-    - { role: interface_config_5_0, when: cord_version == "5.0" }
-    - { role: build_and_run_5_0, when: cord_version == "5.0" }
+    - { role: interface_config_4_1, when: cord_version == 4.1 }
+    - { role: build_and_run_4_1, when: cord_version == 4.1 }
+    - { role: interface_config_5_0, when: cord_version == 5.0 }
+    - { role: build_and_run_5_0, when: cord_version == 5.0 }