Hotfixing bug in wp_save_image() in WordPress 3.5

gistfile1.php

<?php

add_action( 'wp_ajax_image-editor', 'fix_wp_ajax_image_editor', 0 );

function fix_wp_ajax_image_editor() {
  $attachment_id = intval( $_POST['postid'] );

	if ( empty( $attachment_id ) || ! current_user_can( 'edit_post', $attachment_id ) )
		wp_die( -1 );

	check_ajax_referer( "image_editor-$attachment_id" );
	include_once( ABSPATH . 'wp-admin/includes/image-edit.php' );

	$msg = false;
	switch ( $_POST['do'] ) {
		case 'save' :
			$old_meta = wp_get_attachment_metadata( $attachment_id );

			$msg = wp_save_image( $attachment_id );
			$msg = json_encode( $msg );

			break;
		case 'scale' :
			$old_meta = wp_get_attachment_metadata( $attachment_id );

			$msg = wp_save_image( $attachment_id );

			break;
		case 'restore' :
			$msg = wp_restore_image( $attachment_id );
			break;
	}

	if( isset( $old_meta ) ) {
		$new_meta = wp_get_attachment_metadata( $attachment_id );
		$new_meta['sizes'] = array_merge( $old_meta['sizes'], $new_meta['sizes'] );

		wp_update_attachment_metadata( $attachment_id, $new_meta );

		if( 'save' == $_POST['do'] )
			wp_die( $msg );
	}

	wp_image_editor( $attachment_id, $msg );
	wp_die();
}