gistfile1.txt

#!/bin/bash

# Copyright 2022 Google LLC.
# SPDX-License-Identifier: Apache-2.0

set -e
set -o pipefail

if [[ -n "$(git status --porcelain --ignore-submodules)" ]]; then
  echo "Working directory not clean"
  git status
  exit 1
fi
git checkout "${1?}"
git pull upstream "${1?}" --ff-only
git submodule update --init
if [[ -n "$(git status --porcelain --ignore-submodules=dirty)" ]]; then
  echo "Working directory not clean after update"
  git status
  exit 1
fi