From 3f3593aa6c04506943fe743233f184384d99cdd5 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Mon, 1 Apr 2019 16:18:52 +0000
Subject: [PATCH] Customize: Only add `custom-background` to `body_class()` if
 the current theme supports custom background.

Props wido, swissspidy, ocean90, Mte90.
Fixes #38168.
Built from https://develop.svn.wordpress.org/trunk@45088


git-svn-id: http://core.svn.wordpress.org/trunk@44897 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/post-template.php | 3 ++-
 wp-includes/theme.php         | 4 +++-
 wp-includes/version.php       | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/wp-includes/post-template.php b/wp-includes/post-template.php
index b817edec4f..3765e9873c 100644
--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -773,7 +773,8 @@ function get_body_class( $class = '' ) {
 		$classes[] = 'no-customize-support';
 	}
 
-	if ( get_background_color() !== get_theme_support( 'custom-background', 'default-color' ) || get_background_image() ) {
+	if ( current_theme_supports( 'custom-background' )
+		&& ( get_background_color() !== get_theme_support( 'custom-background', 'default-color' ) || get_background_image() ) ) {
 		$classes[] = 'custom-background';
 	}
 
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 9a72126488..23907bc549 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -2730,7 +2730,9 @@ function _remove_theme_support( $feature ) {
 				break;
 			}
 			$support = get_theme_support( 'custom-background' );
-			remove_action( 'wp_head', $support[0]['wp-head-callback'] );
+			if ( isset( $support[0]['wp-head-callback'] ) ) {
+				remove_action( 'wp_head', $support[0]['wp-head-callback'] );
+			}
 			remove_action( 'admin_menu', array( $GLOBALS['custom_background'], 'init' ) );
 			unset( $GLOBALS['custom_background'] );
 			break;
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 063c299588..6d1b73ecef 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.2-beta1-45087';
+$wp_version = '5.2-beta1-45088';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.