pull before using docker image

.github/workflows/docker.yaml

@@ -54,8 +54,6 @@ jobs:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           load: true
 
-      - run: echo Pushed ghcr.io/${{ github.repository }}:${{ steps.build.outputs.tag }}
-
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
@@ -73,6 +71,11 @@ jobs:
           pip install -v --no-deps -e .
 
       - name: Run smoke test
+        # Because of limitations in Docker buildx (which underlies the build-and-push-to-ghcr action),
+        # we can't both push the Docker image and have it available locally in the same build action.
+        # So we have to go pull it from the registry before using it here.
+        # See https://github.com/docker/build-push-action/issues/906#issuecomment-1686036330
         run: |
+          docker pull ghcr.io/${{ github.repository }}@${{ steps.build.outputs.imageid }}
           export BUTLER_SERVER_DOCKER_IMAGE=${{ steps.build.outputs.imageid }}
           python tests_integration/test_docker_container.py