Add python pexpect in prereqs
diff --git a/src/test/setup/prerequisites.sh b/src/test/setup/prerequisites.sh
index a742361..b73017e 100755
--- a/src/test/setup/prerequisites.sh
+++ b/src/test/setup/prerequisites.sh
@@ -17,7 +17,7 @@
echo "Pulling ONOS latest and 1.5"
docker pull onosproject/onos:latest || exit 127
docker pull onosproject/onos:1.5 || exit 127
-apt-get -y install wget git python python-dev python-pip python-setuptools python-scapy tcpdump arping
+apt-get -y install wget git python python-dev python-pip python-setuptools python-scapy python-pexpect tcpdump arping
easy_install nose
apt-get -y install openvswitch-common openvswitch-switch
pip install -U scapy