Removing pull of onos 1.5

Change-Id: I8b87e0503f28fe9ad5eef4b0a7494bbffbefd9be
diff --git a/src/test/setup/prerequisites.sh b/src/test/setup/prerequisites.sh
index 1bfb6dd..30b5a6b 100755
--- a/src/test/setup/prerequisites.sh
+++ b/src/test/setup/prerequisites.sh
@@ -22,9 +22,8 @@
     echo "Verifying Docker installation"
     docker run --rm hello-world || exit 127
     docker rmi hello-world
-    echo "Pulling ONOS latest and 1.5"
+    echo "Pulling ONOS latest"
     docker pull onosproject/onos:latest || exit 127
-    docker pull onosproject/onos:1.5 || exit 127
     apt-get -y install openvswitch-common openvswitch-switch
 fi
 apt-get -y install wget git python python-dev python-pip python-setuptools python-scapy python-pexpect python-maas-client tcpdump arping libssl-dev