Ticket #12634: 12634.diff

wp-includes/post.php

@@ -2787 +2787 @@
                 }
         } elseif ( in_array( $post_type, $hierarchical_post_types ) ) {
                 // Page slugs must be unique within their own trees. Pages are in a separate
-                // namespace than posts so page slugs are allowed to overlap post slugs.
+                // namespace than posts so page slugs are allowed to overlap post slugs. But they must not
+                // overlap slugs of attachments sharing the same parent.
+                $hierarchical_post_types['attachment'] = 'attachment';
+                
                 $check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( '" . implode( "', '", esc_sql( $hierarchical_post_types ) ) . "' ) AND ID != %d AND post_parent = %d LIMIT 1";
                 $post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID, $post_parent ) );