git-go

#!/bin/sh

SUBDIRECTORY_OK=1
OPTIONS_SPEC='git go [options] [branch]
--
b,branch   create and checkout a new branch
'

. "$(git --exec-path)/git-sh-setup"

checkout_opts=

while test "$#" != 0; do
    case "$1" in
        -b|--branch)
            checkout_opts="-b"
        ;;
        --)
            shift
            break
        ;;
        *)
            usage
        ;;
    esac
    shift
done

does_branch_exist() {
    git rev-parse "$1" >/dev/null 2>&1
}

has_upstream() {
    git rev-parse "$1@{upstream}" >/dev/null 2>&1
}

if [ -z "$1" ]; then
    git pull --ff-only
    exit
fi

upstream=origin
branch="$1"
if [ "$#" -gt 1 ]; then
    upstream="$1"
    branch="$2"
fi

git fetch "$upstream" "$branch:$branch" 2>/dev/null &&
if ! has_upstream "$branch"; then
    git branch --set-upstream-to="$upstream/$branch" "$branch"
fi

git checkout $checkout_opts "$branch"