diff --git a/run_tests.sh b/run_tests.sh
index 2acd0b1..502f972 100644
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -1,6 +1,23 @@
 #!/bin/bash
 
-set -eux
+set -ex
+
+#REPLACE_ENV
+
+export ZUUL_PROJECT=${ZUUL_PROJECT:-openstack/nova}
+export ZUUL_BRANCH=${ZUUL_BRANCH:-master}
+export ZUUL_REF=${ZUUL_REF:-HEAD}
+# Values from the job template
+export DEVSTACK_GATE_TEMPEST=${DEVSTACK_GATE_TEMPEST:-1}
+export DEVSTACK_GATE_TEMPEST_FULL=${DEVSTACK_GATE_FULL:-0}
+
+
+export PYTHONUNBUFFERED=true
+export DEVSTACK_GATE_VIRT_DRIVER=xenapi
+# Set gate timeout to 2 hours
+export DEVSTACK_GATE_TIMEOUT=240
+
+set -u
 
 SSH_DOM0="sudo -u domzero ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null root@192.168.33.2"
 FEED_WITH_NOTHING="< /dev/null"
@@ -43,7 +60,6 @@ sudo pip install -i https://pypi.python.org/simple/ XenAPI
 # These came from the Readme
 export REPO_URL=https://review.openstack.org/p
 export ZUUL_URL=/home/jenkins/workspace-cache
-export ZUUL_REF=HEAD
 export WORKSPACE=/home/jenkins/workspace/testing
 
 # Check out a custom branch
@@ -55,13 +71,7 @@ export WORKSPACE=/home/jenkins/workspace/testing
 )
 mkdir -p $WORKSPACE
 
-export ZUUL_PROJECT=openstack/nova
-export ZUUL_BRANCH=master
-
-git clone $REPO_URL/$ZUUL_PROJECT $ZUUL_URL/$ZUUL_PROJECT
-cd $ZUUL_URL/$ZUUL_PROJECT
-git checkout remotes/origin/$ZUUL_BRANCH
-
+function pre_test_hook() {
 # Plugins
 tar -czf - -C /home/jenkins/workspace-cache/nova/plugins/xenserver/xenapi/etc/xapi.d/plugins/ ./ |
     $SSH_DOM0 \
@@ -75,10 +85,6 @@ $SSH_DOM0 crontab - << CRONTAB
 * * * * * /root/rotate_xen_guest_logs.sh
 CRONTAB
 
-# Insert a rule as the first position - allow all traffic on the mgmt interface
-# Other rules are inserted by config/modules/iptables/templates/rules.erb
-sudo iptables -I INPUT 1 -i eth2 -s 192.168.33.0/24 -j ACCEPT
-
 (
     cd /home/jenkins/workspace-cache/devstack
     {
@@ -88,20 +94,16 @@ sudo iptables -I INPUT 1 -i eth2 -s 192.168.33.0/24 -j ACCEPT
         echo "create_directory_for_kernels"
     } | $SSH_DOM0
 )
+}
+
+# Insert a rule as the first position - allow all traffic on the mgmt interface
+# Other rules are inserted by config/modules/iptables/templates/rules.erb
+sudo iptables -I INPUT 1 -i eth2 -s 192.168.33.0/24 -j ACCEPT
 
 cd $WORKSPACE
 git clone https://github.com/matelakat/devstack-gate -b xenserver-integration
 
 #( sudo mkdir -p /opt/stack/new && sudo chown -R jenkins:jenkins /opt/stack/new && cd /opt/stack/new && git clone https://github.com/matelakat/devstack-gate -b xenserver-integration )
 
-# Values from the job template
-export PYTHONUNBUFFERED=true
-export DEVSTACK_GATE_TEMPEST=1
-export DEVSTACK_GATE_TEMPEST_FULL=1
-#export DEVSTACK_GATE_TEMPEST_FULL=0
-export DEVSTACK_GATE_VIRT_DRIVER=xenapi
-# Set gate timeout to 2 hours
-export DEVSTACK_GATE_TIMEOUT=240
-
 cp devstack-gate/devstack-vm-gate-wrap.sh ./safe-devstack-vm-gate-wrap.sh
 ./safe-devstack-vm-gate-wrap.sh
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