Add $wp_query parameter to update_post_thumbnail_cache(). props scrib…

…u. see #19949, fixes that ticket for 3.4.

git-svn-id: http://svn.automattic.com/wordpress/trunk@20646 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post-thumbnail-template.php

@@ -50,9 +50,12 @@ function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
  * Update cache for thumbnails in the current loop
  *
  * @since 3.2
+ *
+ * @param object $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.
  */
-function update_post_thumbnail_cache() {
-	global $wp_query;
+function update_post_thumbnail_cache( $wp_query = null ) {
+	if ( ! $wp_query )
+		$wp_query = $GLOBALS['wp_query'];
 
 	if ( $wp_query->thumbnails_cached )
 		return;