wip update

.github/workflows/pr-checks.yml

@@ -140,7 +140,7 @@ jobs:
           echo "github.head_ref: ${{ github.head_ref }}"
           echo "github.ref: ${{ github.ref }}"
           echo "github.ref_name: ${{ github.ref_name }}"
-          echo "github.base_ref: ${{ github.base_ref }}"
+          echo "github.base_ref: ${{ env.BASE_REF }}"
 
       - id: checkout-base
         name: check out base ref for backport check