Don't order feeds of search results by relevance.

Allow for orderby=relevance to explicitly request relevance.

fixes #7394.

Built from https://develop.svn.wordpress.org/trunk@25668


git-svn-id: http://core.svn.wordpress.org/trunk@25584 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/query.php

@@ -2627,7 +2627,7 @@ class WP_Query {
 		// Order search results by relevance only when another "orderby" is not specified in the query.
 		if ( ! empty( $q['s'] ) ) {
 			$search_orderby = '';
-			if ( ! empty( $q['search_orderby_title'] ) && empty( $q['orderby'] ) )
+			if ( ! empty( $q['search_orderby_title'] ) && ( empty( $q['orderby'] ) && ! $this->is_feed ) || 'relevance' === $q['orderby'] )
 				$search_orderby = $this->parse_search_order( $q );
 
 			/**