Update shared_scripts.yml: If running on MRs, additionally fetch the merge request ref

shared_scripts.yml

@@ -39,7 +39,11 @@ variables:
     -   bash ${CI_PROJECT_DIR}/setup.sh --install-default-plugins
     - fi
     - git submodule add https://gitlab-ci-token:${CI_JOB_TOKEN}@git-ce.rwth-aachen.de/${CI_PROJECT_PATH}.git/ Plugins/${CI_PROJECT_NAME}
-    - cd ${CI_PROJECT_DIR}/Plugins/${CI_PROJECT_NAME} && git checkout ${CI_COMMIT_SHA}
+    - cd ${CI_PROJECT_DIR}/Plugins/${CI_PROJECT_NAME}
+    - if [[ $CI_PIPELINE_SOURCE == "merge_request_event" ]] ; then
+    -   git fetch origin $CI_MERGE_REQUEST_REF_PATH
+    - fi
+    - git checkout ${CI_COMMIT_SHA}
     - cd ${CI_PROJECT_DIR}
     - for i in "${!dependencies[@]}"; do
     -   git submodule add -b "${i%%@*}" ${dependencies[$i]} Plugins/${i#*@}