Make gerrit_refspec parameters optional

Change-Id: If3dbd009d59f75d9b9f9556c5ece32a40890a383
Issue-ID: INT-584
Signed-off-by: Gary Wu <gary.i.wu@huawei.com>
diff --git a/deployment/heat/onap-oom/env/tlab/onap-oom.env b/deployment/heat/onap-oom/env/tlab/onap-oom.env
index 04fa44d..d50f3f6 100644
--- a/deployment/heat/onap-oom/env/tlab/onap-oom.env
+++ b/deployment/heat/onap-oom/env/tlab/onap-oom.env
@@ -14,6 +14,8 @@
 
   oam_network_cidr: 10.0.0.0/16
 
+  integration_gerrit_branch: master
+
   helm_deploy_delay: 4m
 
   integration_override_yaml: >