[VOL-2917] fix test script for DT workflow

Change-Id: I3b0cf8555c80e07078b3fa50336c3307cb212259
diff --git a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
index 455566a..f086bcc 100644
--- a/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
+++ b/jjb/pipeline/voltha-dt-physical-functional-tests.groovy
@@ -56,7 +56,7 @@
           )
         sh returnStdout: false, script: """
         cd voltha
-        git clone -b ${branch} ${cordRepoUrl}/cord-tester
+        git clone -b master ${cordRepoUrl}/cord-tester
         mkdir -p $WORKSPACE/bin
         bash <( curl -sfL https://raw.githubusercontent.com/boz/kail/master/godownloader.sh) -b "$WORKSPACE/bin"
         cd $WORKSPACE