From c2e1bab509dbc07a55c58ffee225c227c3b5185a Mon Sep 17 00:00:00 2001
From: Scott Taylor <scott.c.taylor@mac.com>
Date: Thu, 17 Sep 2015 21:32:24 +0000
Subject: [PATCH] Canonical: redirect URLs that match an attachment masked on
 the wrong URL to the attachment link for the matched attachment.

Props solarissmoke.
Fixes #19918.

Built from https://develop.svn.wordpress.org/trunk@34272


git-svn-id: http://core.svn.wordpress.org/trunk@34236 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/canonical.php | 12 +++++++++---
 wp-includes/version.php   |  2 +-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/wp-includes/canonical.php b/wp-includes/canonical.php
index 4c981f9a38..0818124973 100644
--- a/wp-includes/canonical.php
+++ b/wp-includes/canonical.php
@@ -150,9 +150,15 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 
 	} elseif ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) {
 		// rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101
-		if ( is_attachment() && !empty($_GET['attachment_id']) && ! $redirect_url ) {
-			if ( $redirect_url = get_attachment_link(get_query_var('attachment_id')) )
-				$redirect['query'] = remove_query_arg('attachment_id', $redirect['query']);
+		if ( is_attachment() && ! $redirect_url ) {
+			if ( ! empty( $_GET['attachment_id'] ) ) {
+				$redirect_url = get_attachment_link( get_query_var( 'attachment_id' ) );
+				if ( $redirect_url ) {
+					$redirect['query'] = remove_query_arg( 'attachment_id', $redirect['query'] );
+				}
+			} else {
+				$redirect_url = get_attachment_link();
+			}
 		} elseif ( is_single() && !empty($_GET['p']) && ! $redirect_url ) {
 			if ( $redirect_url = get_permalink(get_query_var('p')) )
 				$redirect['query'] = remove_query_arg(array('p', 'post_type'), $redirect['query']);
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7573c6503c..89d8f5ff12 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34271';
+$wp_version = '4.4-alpha-34272';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.