Index: wp-includes/theme.php
===================================================================
--- wp-includes/theme.php	(revision 22260)
+++ wp-includes/theme.php	(working copy)
@@ -1025,7 +1025,27 @@
  * @return object
  */
 function get_custom_header() {
-	$data = is_random_header_image()? _get_random_header_data() : get_theme_mod( 'header_image_data' );
+	global $_wp_default_headers;
+
+	if ( is_random_header_image() ) {
+		$data = _get_random_header_data();
+	} else {
+		$data = get_theme_mod( 'header_image_data' );
+		if ( ! $data && current_theme_supports( 'custom-header', 'default-image' ) ) {
+			$directory_args = array( get_template_directory_uri(), get_stylesheet_directory_uri() );
+			$default_image = vsprintf( get_theme_support( 'custom-header', 'default-image' ), $directory_args );
+			foreach ( $_wp_default_headers as $header => $details ) {
+				$url = vsprintf( $details['url'], $directory_args );
+				if ( $default_image == $url ) {
+					$data = $details;
+					$data['url'] = $url;
+					$data['thumbnail_url'] = vsprintf( $data['thumbnail_url'], $directory_args );
+					break;
+				}
+			}
+		}
+	}
+
 	$default = array(
 		'url'           => '',
 		'thumbnail_url' => '',
Index: wp-content/themes/twentyten/header.php
===================================================================
--- wp-content/themes/twentyten/header.php	(revision 22260)
+++ wp-content/themes/twentyten/header.php	(working copy)
@@ -84,6 +84,7 @@
 						echo get_the_post_thumbnail( $post->ID );
 					elseif ( get_header_image() ) :
 						// Compatibility with versions of WordPress prior to 3.4.
+						var_dump( get_custom_header() );
 						if ( function_exists( 'get_custom_header' ) ) {
 							$header_image_width  = get_custom_header()->width;
 							$header_image_height = get_custom_header()->height;