Resolve #3407052 ".gitlab ci.yml test recommendations mr"

Closes #3407052

.gitlab-ci.yml

@@ -182,6 +182,13 @@ composer:
     - git pull
     - NEXT_RECOMMENDATIONS_VERSION=$(git rev-list --max-count=1 --abbrev-commit HEAD)
     - cp recommendations.json recommendations-next-$NEXT_RECOMMENDATIONS_VERSION.json
+    # Make the recommendations MR of the same issue fork available, if any.
+    # https://git.drupalcode.org/help/user/project/merge_requests/reviews/index#checkout-locally-by-adding-a-git-alias
+    - |
+      if [ "$CI_MERGE_REQUEST_IID" ]; then
+        git remote add issue-fork $CI_MERGE_REQUEST_SOURCE_PROJECT_URL
+        git fetch issue-fork
+      fi
     # Then, check out the pinned version.
     - git checkout -q $AMA__RECOMMENDATIONS__VERSION
     - cp recommendations.json recommendations-pinned-$AMA__RECOMMENDATIONS__VERSION.json