Update PR label notifier (#1964)

Include the list of labels.

.github/process_commit.py

+#!/usr/bin/env python3
 """
 This script finds the merger responsible for labeling a PR by a commit SHA. It is used by the workflow in
 '.github/workflows/pr-labels.yml'. If there exists no PR associated with the commit or the PR is properly labeled,
@@ -60,14 +61,26 @@ def get_pr_merger_and_labels(pr_number: int) -> Tuple[str, Set[str]]:
     return merger, labels
 
 
-if __name__ == "__main__":
+def _get_formatted(l):
+    return ', '.join(f'`{i}`' for i in l)
+
+
+def _main():
     commit_hash = sys.argv[1]
     pr_number = get_pr_number(commit_hash)
     if not pr_number:
-        sys.exit(0)
+        return
 
     merger, labels = get_pr_merger_and_labels(pr_number)
     is_properly_labeled = bool(PRIMARY_LABELS.intersection(labels) and SECONDARY_LABELS.intersection(labels))
 
     if not is_properly_labeled:
-        print(f"@{merger}")
+        print(f"""Hi @{merger}
+
+You merged this PR, but one or more labels are missing.
+Please include a primary label ({_get_formatted(PRIMARY_LABELS)}) and a secondary label ({_get_formatted(SECONDARY_LABELS)}).
+""")  # noqa: E501
+
+
+if __name__ == "__main__":
+    _main()

.github/workflows/pr-labels.yml

@@ -21,15 +21,12 @@ jobs:
 
       - name: Process commit and find merger responsible for labeling
         id: commit
-        run: echo "::set-output name=merger::$(python .github/process_commit.py ${{ github.sha }})"
+        run: echo "::set-output name=message::$(python .github/process_commit.py ${{ github.sha }})"
 
       - name: Ping merger responsible for labeling if necessary
-        if: ${{ steps.commit.outputs.merger != '' }}
+        if: ${{ steps.commit.outputs.message != '' }}
         uses: mshick/add-pr-comment@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
-          message: |
-            Hey ${{ steps.commit.outputs.merger }}!
-            You merged this PR, but labels were not properly added. Please add a primary and secondary label
-            (See https://github.com/pytorch/audio/blob/main/.github/process_commit.py)
+          message: ${{ steps.commit.outputs.message }}