openstack backport script from Vish

bp.sh

#!/usr/bin/env bash
# This little script is to make backporting patches easier.
# Instructions
# ------------
# Make sure that <btranch> exists:
#   git branch -D <branch>
#   git checkout -b <branch> origin/<branch>
# Grab the file and stick it in your <project> directory:
#   curl -OL https://raw.github.com/gist/2206428/bp.sh
# Make sure the script is runnable:
#   chmod 755 bp.sh
# Start backporting reviews:
#   ./bp.sh <review_number>
# Recovering from errors
# ----------------------
# If your branch fails to merge cleanly it is usually due to
# a dependent branch not being in yet.  In that case your best bet
# is to wait for the dependent branch to merge and rerun the script.

if [ -z "$1" ]; then
    echo "Usage: $0 <review_number> [branch]"
    echo "    review_number: numeric review number from gerrit"
    echo "    branch: target gerrit branch (defaults to milestone-proposed)"
    exit 1
fi

BRANCH=${2-milestone-proposed}

git checkout $BRANCH
git pull
git branch -D bp-$1
git checkout -b bp-$1
git review -X $1
git review $BRANCH
REMOTE=`git remote show gerrit -n | grep Fetch | cut -d'/' -f3`
PORT=`echo $REMOTE | cut -d':' -f2`
HOST=`echo $REMOTE | cut -d':' -f1`
SHA=`git rev-parse HEAD`
echo "Use the following line to approve the review"
echo "ssh -p $PORT $HOST gerrit review --code-review +2 --approved +1 $SHA"