Checkout branch from pull request number

git-pr-checkout

#!/bin/bash

pr=$1

if [ ! $pr ]; then
  echo "Require PR number."
  exit 1
fi
pr=`sed -E "s%^.*pulls?/%%g; s%/files$%%" <<< $pr` # GitHub の URL だった場合に PR 番号を抜き出す

ref=`git ls-remote | grep refs/pull/${pr}/head | cut -f 1`
if [[ -z `git show-ref | grep origin | grep $ref | cut -f 1` ]]; then
  echo "$ref Not found local repository."
  echo "Fetching..."
  git fetch
fi

branch_name=`git show $ref --quiet --format='%D' | sed -e 's%origin/%%' -e 's/, .*$//'`
if [[ -n `echo $branch_name | grep HEAD` ]]; then
  echo "Target branch checkouted"
  exit 1
fi

git checkout $branch_name