line count change for current git branch

.bash_profile

function parse_git_branch () {
	local git_status="`git status -unormal 2>&1`"

	# http://toucware.blogspot.com/2012/05/partial-string-matching-in-bash.html
	#
	# TODO Catch case when repo is initialized but not committed.
	if [[ "$git_status" == fatal* ]] ; then
		echo ""
	else
		# http://stackoverflow.com/a/11958481/672403
		git rev-parse --symbolic-full-name --abbrev-ref HEAD
	fi
}

# get line count relative to `upstream`
function branchstat () {
	if [ "$#" -eq 0 ] ; then :
		local upstream="master"
	else
		local upstream=$1
	fi

	local branch="$(parse_git_branch)"

	# http://www.cyberciti.biz/faq/linux-unix-appleosx-bsd-bash-passing-variables-to-awk/
	git log --numstat --pretty="%H" $upstream..$branch | awk -v branch=$branch -v upstream=$upstream 'NF==3 {plus+=$1; minus+=$2} END {printf("%s...%s: +%d, -%d, net %d\n", upstream, branch, plus, minus, (plus - minus))}'
}