Ticket #38557: 38557.4.diff

src/wp-admin/custom-header.php

@@ -639 +639 @@
 </tr>
         <?php endif;
 
-        $default_image = get_theme_support( 'custom-header', 'default-image' );
+        $default_image = sprintf( get_theme_support( 'custom-header', 'default-image' ), get_template_directory_uri(), get_stylesheet_directory_uri() );
         if ( $default_image && get_header_image() != $default_image ) : ?>
 <tr>
 <th scope="row"><?php _e( 'Reset Image' ); ?></th>

src/wp-includes/class-wp-customize-manager.php

@@ -3439 +3439 @@
                 ) );
 
                 $this->add_setting( new WP_Customize_Filter_Setting( $this, 'header_image', array(
-                        'default'        => get_theme_support( 'custom-header', 'default-image' ),
+                        'default'        => sprintf( get_theme_support( 'custom-header', 'default-image' ), get_template_directory_uri(), get_stylesheet_directory_uri() ),
                         'theme_supports' => 'custom-header',
                 ) ) );
 
                 $this->add_setting( new WP_Customize_Header_Image_Setting( $this, 'header_image_data', array(
-                        // 'default'        => get_theme_support( 'custom-header', 'default-image' ),
                         'theme_supports' => 'custom-header',
                 ) ) );