Make sure we use the right tempest

Make sure we use a tempest that supports python2
if we are in a python2 env

Change-Id: I4cdbef075bc4fcf81837bbd7e69543feaec89178

devstack/plugin.sh

@@ -348,6 +348,17 @@ if is_service_enabled vitrage; then
         init_vitrage
         # Start the services
         start_vitrage
+
+        # this is a hack!!! latest tempest doesn't support
+        # python2 make sure we have a tempest that support python2
+        # if we are in a python2 env
+        if ! python3_enabled; then
+          pushd .
+          cd $TEMPEST_DIR
+          git checkout 23.0.0
+          popd
+        fi
+
     fi
 
     if [[ "$1" == "unstack" ]]; then