create required branch explicitly

.github/workflows/check-task-migration.yaml

@@ -10,24 +10,13 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - name: Get changed files
-        id: changed-files
-        uses: tj-actions/changed-files@v45
-      - name: show files
-        env:
-          ADDED_FILES: ${{ steps.changed-files.outputs.added_files }}
-          ALL_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
-        run: |
-          echo "added files:"
-          echo ${ADDED_FILES}
-          echo
-          echo "changed files:"
-          echo ${ALL_CHANGED_FILES}
-          echo
-          git log main
       - name: Create k8s Kind Cluster
         uses: helm/kind-action@v1
       - name: Run check
         run: |
+          # Require name main
+          git branch main origin/main
+          # Make `git branch --show-current` works.
+          git checkout -b pr-verify
           export IN_CLUSTER=1
           bash -x ./hack/validate-migration.sh

hack/validate-migration.sh

@@ -30,7 +30,8 @@ declare -r BUILD_PIPELINE_CONFIG=https://raw.githubusercontent.com/redhat-appstu
 WORK_DIR=$(mktemp -d --suffix=-validate-migrations)
 declare -r WORK_DIR
 
-declare -r DEFAULT_BRANCH=main
+: "${DEFAULT_BRANCH:=main}"
+declare -r DEFAULT_BRANCH
 
 # By default, do not run with a real kubernetes cluster.
 : "${IN_CLUSTER:=""}"