Ticket #13961: 13961.3.patch

wp-includes/query.php

@@ -2178 +2178 @@
                 if ( !empty($q['s']) ) {
                         // added slashes screw with quote grouping when done early, so done later
                         $q['s'] = stripslashes($q['s']);
+                        if ( empty( $_GET['s'] ) && is_main_query() )
+                                $q['s'] = urldecode($q['s']);
                         if ( !empty($q['sentence']) ) {
                                 $q['search_terms'] = array($q['s']);
                         } else {