Fix warning about GERRIT_BRANCH parameter not set in devops-stages/stage-test.sh

Change-Id: Ia18af15a204c37283086a9328d3b97e764cdfb8f
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>

devops-stages/stage-test.sh

@@ -22,6 +22,8 @@ CURRENT_DIR=`pwd`
 CHARM_PATH="./installers/charm"
 NEW_CHARMS_NAMES="osm-keystone osm-lcm osm-mon osm-nbi osm-ng-ui osm-pol osm-ro vca-integrator-operator"
 OLD_CHARMS_NAMES="prometheus grafana"
+LOCAL_GIT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+GERRIT_BRANCH=${GERRIT_BRANCH:-${LOCAL_GIT_BRANCH}}
 for charm in $NEW_CHARMS_NAMES; do
     if [ $(git diff --name-only "origin/${GERRIT_BRANCH}" -- "installers/charm/${charm}" | wc -l) -ne 0 ]; then
         echo "Running tox for ${charm}"