Add BUILD_BRANCH variable

* This variable allows to define the branch that is used for the
manifest build (the master one on schedule/tag or the integration one on
upstream pipeline trigger)

manifest-pipeline-yocto.yml

@@ -186,9 +186,14 @@ retrigger:
       - eval $(ssh-agent -s)
       - ssh-add /home/secous/.ssh/id_rsa
       - export EULA=1
+      - BUILD_BRANCH=${MASTER_BRANCH}
+      - |
+         if [ ${CI_PIPELINE_SOURCE} == "pipeline" ]; then
+            echo "This is the manifest branch used for the build ${CI_COMMIT_REF_NAME}"
+            BUILD_BRANCH="${CI_COMMIT_REF_NAME}"
       - |
         su secous -c "
-        repo init -u ${CI_REPOSITORY_URL} -b kirkstone/develop; 
+        repo init -u ${CI_REPOSITORY_URL} -b ${BUILD_BRANCH}; 
         repo sync -j$(nproc) --fetch-submodules;
         . ./seco-setup.sh -d ${DEFCONFIG_FILE};
         . ./seco-setup.sh -c;