自4.3升级以来Wordpress密码重置

I've been using a Wordpress tutorial to build a suitable login and pawords reset process as outlined here:

http://code.tutsplus.com/tutorials/build-a-custom-wordpress-user-flow-part-1-replace-the-login-page--cms-23627

It worked super well until upgrade to Wordpress 4.3 in when the password reset stopped working and I now get an invalid key error message.

I have presumed that the mechanism has changed since the upgrade/ use of hashing/password expiration but cant seem to find any documentation. Does anyone know how to fix this, the password reset is outlined below:

     /**
     * Resets the user's password if the password reset form was submitted.
     */
    public function do_password_reset() {
        if ( 'POST' == $_SERVER['REQUEST_METHOD'] ) {
            $rp_key = $_REQUEST['rp_key'];
            $rp_login = $_REQUEST['rp_login'];

            $user = check_password_reset_key( $rp_key, $rp_login );

            if ( ! $user || is_wp_error( $user ) ) {
                if ( $user && $user->get_error_code() === 'expired_key' ) {
                    wp_redirect( home_url( 'member-login?login=expiredkey' ) );
                } else {
                    wp_redirect( home_url( 'member-login?login=invalidkey' ) );
                }
                exit;
            }

        // Reset password
                reset_password( $user, $_POST['pass1'] );
                wp_redirect( home_url( 'member-login?password=changed' ) );
            } else {
                echo "Invalid request.";
            }

            exit;
        }
    }