Reverted and changed way to store variable

.github/workflows/gitlab_ci.yml

@@ -90,9 +90,9 @@ jobs:
           echo "Git pull"
           git pull
           echo "New branch shall be named: TEMPORARY_MERGE_PR_${{ github.event.number }}"
-          echo "MIRROR_BRANCH=TEMPORARY_MERGE_PR_${{ github.event.number }}" >> "$GITHUB_ENV"
-          echo "Create new branch ${{ MIRROR_BRANCH }} and check it out"
-          git checkout -b "${{ MIRROR_BRANCH }}"
+          echo "MIRROR_BRANCH=TEMPORARY_MERGE_PR_$github.event.number" >> $GITHUB_ENV
+          echo "Create new branch ${{ env.MIRROR_BRANCH }} and check it out"
+          git checkout -b "${{ env.MIRROR_BRANCH }}"
           git merge --ff-only "${{ github.event.pull_request.head.sha }}"
       - name: Mirror and wait for Gitlab-CI
         uses: jakob-fritz/github2lab_action@Iss37_variable_for_checkout
@@ -103,4 +103,4 @@ jobs:
           GITLAB_HOSTNAME: "gitlab.jsc.fz-juelich.de"
           GITLAB_PROJECT_ID: "6029"
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          MIRROR_BRANCH: ${{ MIRROR_BRANCH }}
+          MIRROR_BRANCH: ${{ env.MIRROR_BRANCH }}