Merge "Don't say "update package missing" unless we mean it."

    setup_requirements(reinterpret_cast<char*>(data), sz);

    for (size_t i = 0; i < ARRAY_SIZE(images); i++) {

    for (size_t i = 0; i < ARRAY_SIZE(images); ++i) {

        int fd = unzip_to_file(zip, images[i].img_name);

        if (fd < 0) {

            if (images[i].is_optional)

        if (fd == -1) {

            if (images[i].is_optional) {

                continue;

            die("update package missing %s", images[i].img_name);

            }

            exit(1); // unzip_to_file already explained why.

        }

        fastboot_buffer buf;

        int rc = load_buf_fd(usb, fd, &buf);