git-rebranch

#!/usr/bin/env bash
set -e
newbranch=$1
remote=${2:-origin/master}

if [[ -z $newbranch || -z $remote ]]; then
    echo usage: git rebranch NAME REMOTE-BRANCH
    echo
    echo example: git branch mybranch origin/master
    echo
    echo "This preserves current working tree changes in a stash,"
    echo "then creates a new branch tracking origin/master so that"
    echo "you can work in a fresh tree."
    exit 1
fi

if [[ ! $remote =~ "/" ]]; then
    echo "The remote argument should be of the form: remote/branch."
    echo "For example: origin/master"
    exit 1
fi

git stash                   # stash away working tree changes

git checkout -b $newbranch -t $remote