Simple git merge with squash for Jenkins repos

jenkins-merge-pr.sh

#!/bin/bash -ex

REPO_NAME=${PWD##*/}
TARGET_ORG="jenkinsci"

#TODO: fetch from GitHib API
#TODO: if no, process parameters correctly
GITHUB_PR_NUMBER=${1}
FROM_USER=${2}
BRANCH=${3}
MESSAGE=${4}
echo "Merging ${FROM_USER}/${REPO_NAME}, branch ${BRANCH}"

GITHUB_USER_REPO_URL="https://github.com/${FROM_USER}/${REPO_NAME}"
GITHUB_TARGET_REPO_URL="https://github.com/${TARGET_ORG}/${REPO_NAME}"

LOCAL_REMOTE="jenkins-merge_${FROM_USER}_${BRANCH}"
LOCAL_BRANCH="${LOCAL_REMOTE}/${BRANCH}"
GITHUB_PR_URL="${GITHUB_TARGET_REPO_URL}/pull/${GITHUB_PR_NUMBER}"

# Init repo for merge
git remote remove "${LOCAL_REMOTE}" || res=$?
git remote add "${LOCAL_REMOTE}" "${GITHUB_USER_REPO_URL}"
git fetch "${LOCAL_REMOTE}"

# Extract data
PR_AUTHOR=$(git log "${LOCAL_BRANCH}" | sed -n '2p' | sed "s/^\s*Author:\s*//")

# Perform merge
git merge --squash "${LOCAL_BRANCH}"
git commit -a --author="${PR_AUTHOR}" --message="${MESSAGE}.

This pull request integrates ${GITHUB_PR_URL}"

# Cleanup
#TODO: It's unreliable, of course
git remote remove "${LOCAL_REMOTE}"