Ticket #16728: 16728.diff

wp-includes/canonical.php

@@ -78 +78 @@
                                 $redirect['query'] = remove_query_arg(array('p', 'page_id', 'attachment_id', 'post_type'), $redirect['query']);
                 }
         }
+           
+        if( is_category() ) {
+                if( isset( $_GET['category_name'] ) ) {
+                        $categories = explode( ',', $_GET['category_name'] );
+                        $categories = "'" . implode( "','", array_map( 'sanitize_title_for_query', $categories ) ) . "'";
+                        $category_ids = $wpdb->get_col( "SELECT term_id FROM $wpdb->term_taxonomy INNER JOIN $wpdb->terms USING(term_id) WHERE taxonomy='category' AND slug IN($categories)" );
+                        if( $category_ids ) {
+                                $redirect_url = home_url( '/' );
+                                $redirect_url = add_query_arg( array( 'cat' => implode( ',', $category_ids ) ), $redirect_url );
+                                $redirect['query'] = remove_query_arg( array( 'cat', 'category_name', 'category' ), $redirect['query'] );
+                        }
+                }
+        }
 
         // These tests give us a WP-generated permalink
         if ( is_404() ) {