fixup, skip matrix if there are no jobs in it

Author: jiridanek

.github/workflows/build-notebooks-pr.yaml

@@ -14,6 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       matrix: ${{ steps.gen.outputs.matrix }}
+      has_jobs: ${{ steps.gen.outputs.has_jobs }}
     steps:
       - uses: actions/checkout@v4
 
@@ -27,13 +28,13 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
-  # base images
   build:
     needs: ["gen"]
     strategy:
       fail-fast: false
       matrix: "${{ fromJson(needs.gen.outputs.matrix) }}"
     uses: ./.github/workflows/build-notebooks-TEMPLATE.yaml
+    if: ${{ fromJson(needs.gen.outputs.has_jobs) }}
     with:
       target: "${{ matrix.target }}"
       github: "${{ toJSON(github) }}"

ci/cached-builds/gen_gha_matrix_jobs.py

@@ -144,7 +144,8 @@ def print_github_actions_pr_matrix(tree: dict[str, list[str]], leafs: list[str])
         targets.append(leaf)
 
     matrix = {"target": targets}
-    return [f"matrix={json.dumps(matrix, separators=(',', ':'))}"]
+    return [f"matrix={json.dumps(matrix, separators=(',', ':'))}",
+            f"has_jobs={json.dumps(len(leafs) > 0, separators=(',', ':'))}"]
 
 
 def main() -> None: