From ab8cff782774ddb45aad9fe7cdf49b877ca88f26 Mon Sep 17 00:00:00 2001
From: Pascal Birchler <swissspidy@git.wordpress.org>
Date: Thu, 17 Dec 2015 18:12:50 +0000
Subject: [PATCH] In `WP::handle_404()`, make sure `$wp_query->post` is a
 `WP_Post` object before cloning it.

Props igmoweb for initial patch.
See #35013.

git-svn-id: https://develop.svn.wordpress.org/trunk@35994 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp.php | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/class-wp.php b/src/wp-includes/class-wp.php
index 06c59bd7b7..9f6172deac 100644
--- a/src/wp-includes/class-wp.php
+++ b/src/wp-includes/class-wp.php
@@ -609,7 +609,12 @@ class WP {
 
 			$success = true;
 			if ( is_singular() ) {
-				$p = clone $wp_query->post;
+				$p = false;
+
+				if ( $wp_query->post instanceof WP_Post ) {
+					$p = clone $wp_query->post;
+				}
+
 				// Only set X-Pingback for single posts that allow pings.
 				if ( $p && pings_open( $p ) ) {
 					@header( 'X-Pingback: ' . get_bloginfo( 'pingback_url' ) );