git-sign() {
	case $# in
		"0") range=HEAD ;;
		"1") range=$1 ;;
		 * ) echo "too many arguments" 1>&2; return 1 ;;
	esac

	# In git-2.8.4, it should be possible to drop the -i option ,
	# along with the override of EDITOR:
	# https://git.kernel.org/cgit/git/git.git/commit/?h=next&id=78ec240020db4bdd773830f3d41f4b4bdf9a4e2d
	EDITOR=true git rebase -i "$range" --exec "git commit --amend --no-edit --gpg-sign" \
		|| git rebase --abort
}