diff -r cf61fcea0001 -r c7c34916027a wp/wp-content/themes/twentyfifteen/inc/back-compat.php
--- a/wp/wp-content/themes/twentyfifteen/inc/back-compat.php	Mon Oct 14 17:39:30 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,63 +0,0 @@
-<?php
-/**
- * Twenty Fifteen back compat functionality
- *
- * Prevents Twenty Fifteen from running on WordPress versions prior to 4.1,
- * since this theme is not meant to be backward compatible beyond that and
- * relies on many newer functions and markup changes introduced in 4.1.
- *
- * @package WordPress
- * @subpackage Twenty_Fifteen
- * @since Twenty Fifteen 1.0
- */
-
-/**
- * Prevent switching to Twenty Fifteen on old versions of WordPress.
- *
- * Switches to the default theme.
- *
- * @since Twenty Fifteen 1.0
- */
-function twentyfifteen_switch_theme() {
-	switch_theme( WP_DEFAULT_THEME, WP_DEFAULT_THEME );
-	unset( $_GET['activated'] );
-	add_action( 'admin_notices', 'twentyfifteen_upgrade_notice' );
-}
-add_action( 'after_switch_theme', 'twentyfifteen_switch_theme' );
-
-/**
- * Add message for unsuccessful theme switch.
- *
- * Prints an update nag after an unsuccessful attempt to switch to
- * Twenty Fifteen on WordPress versions prior to 4.1.
- *
- * @since Twenty Fifteen 1.0
- */
-function twentyfifteen_upgrade_notice() {
-	$message = sprintf( __( 'Twenty Fifteen requires at least WordPress version 4.1. You are running version %s. Please upgrade and try again.', 'twentyfifteen' ), $GLOBALS['wp_version'] );
-	printf( '<div class="error"><p>%s</p></div>', $message );
-}
-
-/**
- * Prevent the Customizer from being loaded on WordPress versions prior to 4.1.
- *
- * @since Twenty Fifteen 1.0
- */
-function twentyfifteen_customize() {
-	wp_die( sprintf( __( 'Twenty Fifteen requires at least WordPress version 4.1. You are running version %s. Please upgrade and try again.', 'twentyfifteen' ), $GLOBALS['wp_version'] ), '', array(
-		'back_link' => true,
-	) );
-}
-add_action( 'load-customize.php', 'twentyfifteen_customize' );
-
-/**
- * Prevent the Theme Preview from being loaded on WordPress versions prior to 4.1.
- *
- * @since Twenty Fifteen 1.0
- */
-function twentyfifteen_preview() {
-	if ( isset( $_GET['preview'] ) ) {
-		wp_die( sprintf( __( 'Twenty Fifteen requires at least WordPress version 4.1. You are running version %s. Please upgrade and try again.', 'twentyfifteen' ), $GLOBALS['wp_version'] ) );
-	}
-}
-add_action( 'template_redirect', 'twentyfifteen_preview' );