Gitlab getting merged branch name

gitlab_previous_branch.sh

  - MR_BRANCH_LAST_COMMIT_SHA=$(
      curl -s \
        --header "PRIVATE-TOKEN: $CI_PRIVATE_TOKEN" \
        "$CI_API_V4_URL/projects/$CI_PROJECT_ID/repository/commits/$CI_COMMIT_SHA" |\
        jq -r '.parent_ids | del(.[] | select(. == "'$CI_COMMIT_BEFORE_SHA'")) | .[-1]'
    )
  - MR_BRANCH_NAME=$(
      curl -s \
        --header "PRIVATE-TOKEN: $CI_PRIVATE_TOKEN" \
        "$CI_API_V4_URL/projects/$CI_PROJECT_ID/repository/commits/$MR_BRANCH_LAST_COMMIT_SHA/merge_requests" |\
        jq -r '.[0].source_branch'
    )