function do_robots() {
	header( 'Content-Type: text/plain; charset=utf-8' );

	/**
	 * Fires when displaying the robots.txt file.
	 *
	 * @since 2.1.0
	 */
	do_action( 'do_robotstxt' );

	$output = "User-agent: *\n";
	$public = get_option( 'blog_public' );
	if ( '0' == $public ) {
		$output .= "Disallow: /\n";
	} else {
		$site_url = parse_url( site_url() );
		$path = ( !empty( $site_url['path'] ) ) ? $site_url['path'] : '';
		$output .= "Disallow: $path/wp-admin/\n";
		$output .= "Disallow: $path/wp-includes/\n";
	}

	/**
	 * Filter the robots.txt output.
	 *
	 * @since 3.0.0
	 *
	 * @param string $output Robots.txt output.
	 * @param bool   $public Whether the site is considered "public".
	 */
	echo apply_filters( 'robots_txt', $output, $public );
}

/**
 * Test whether blog is already installed.
 *
 * The cache will be checked first. If you have a cache plugin, which saves the
 * cache values, then this will work. If you use the default WordPress cache,
 * and the database goes away, then you might have problems.
 *
 * Checks for the option siteurl for whether WordPress is installed.
 *
 * @since 2.1.0
 * @uses $wpdb
 *
 * @return bool Whether blog is already installed.