From 46c375f4604559e68f85b8576499c5f7c1dae9af Mon Sep 17 00:00:00 2001
From: Andrei Vagin <avagin@google.com>
Date: Mon, 6 Mar 2023 17:28:13 -0800
Subject: [PATCH] buildkite: don't run tests on deleted branches

Copybara updates a target branch before merging it to the master
and then it deletes it. The problem is that it triggers buildkite
twice on the same commit: on the master branch and on
the target branch.

PiperOrigin-RevId: 514573062
---
 .buildkite/hooks/pre-command | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/.buildkite/hooks/pre-command b/.buildkite/hooks/pre-command
index c79bc3a25..0a9ee356b 100644
--- a/.buildkite/hooks/pre-command
+++ b/.buildkite/hooks/pre-command
@@ -1,5 +1,11 @@
 set -euo pipefail
 
+# Check that the target branch exists.
+git fetch origin "${BUILDKITE_BRANCH}" || {
+  echo "Branch ${BUILDKITE_BRANCH} no longer exists; it was probably deleted by the time we got to it." >&2
+  exit 1
+}
+
 # Download any build-specific configuration that has been uploaded.
 # This allows top-level steps to override all subsequent steps.
 buildkite-agent artifact download 'tools/bazeldefs/*' . || true