From 7f05dc1515aa46aa279cee92b99ffb9c68f5c144 Mon Sep 17 00:00:00 2001
From: Victor Lin <13424970+victorlin@users.noreply.github.com>
Date: Mon, 21 Oct 2024 10:02:42 -0700
Subject: [PATCH] Prevent concurrent workflow runs on the same PR

The previous concurrency key mostly did this, but did not consider that
the PR's ref changes when a pull request is merged. In practice, this
meant that closing/merging the PR shortly shortly after updating it
would trigger two workflow runs. Only the latest run (cleanup) should
continue.
---
 .github/workflows/preview_on_downstream_repo.yaml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/preview_on_downstream_repo.yaml b/.github/workflows/preview_on_downstream_repo.yaml
index 91e4712a1..e57dbd2c5 100644
--- a/.github/workflows/preview_on_downstream_repo.yaml
+++ b/.github/workflows/preview_on_downstream_repo.yaml
@@ -13,9 +13,9 @@ on:
         required: true
         type: boolean
 
-# Cancel any in-progress runs of a caller workflow on the same branch.
+# Cancel any in-progress runs of a caller workflow on the same pull request.
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.number }}
   cancel-in-progress: true
 
 env: