Fix/docker repo url3 (#3297)

* Make repo url work in merge queue ci, which is not a pull request....

* dump context

.github/workflows/docker-ci.yaml

@@ -19,6 +19,11 @@ jobs:
       - uses: actions/checkout@v3
         with:
           submodules: recursive
+      - name: Dump github context
+        run:   echo "$GITHUB_CONTEXT"
+        shell: bash
+        env:
+          GITHUB_CONTEXT: ${{ toJson(github) }}
 
       - name: Test build_image.sh script with custom tagging and gpu flag
         working-directory: docker
@@ -39,7 +44,10 @@ jobs:
         working-directory: docker
         run: |
           IMAGE_TAG=test-image-${{ matrix.python-version }}
-          REPO_URL=${{ github.event.pull_request.head.repo.clone_url }}
+          REPO_URL="${{ github.event.pull_request.head.repo.clone_url }}"
+          if [[ -z "${REPO_URL}" ]]; then
+            REPO_URL="https://github.com/pytorch/serve.git"
+          fi
           ./build_image.sh -py "${{ matrix.python-version }}" -t "${IMAGE_TAG}" -b "${{ steps.branch-name.outputs.GITHUB_BRANCH }}" -repo ${REPO_URL} -s
           echo "IMAGE_TAG=${IMAGE_TAG}" >> $GITHUB_OUTPUT