Index: modules/comment/comment.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.module,v
retrieving revision 1.663
diff -u -p -r1.663 comment.module
--- modules/comment/comment.module  15 Nov 2008 11:45:03 -0000  1.663
+++ modules/comment/comment.module  15 Nov 2008 15:38:04 -0000
@@ -747,7 +747,7 @@ function comment_save($edit) {
         if ($edit['pid'] == 0) {
           // This is a comment with no parent comment (depth 0): we start
           // by retrieving the maximum thread level.
-          $max = db_query('SELECT MAX(thread) FROM {comments} WHERE nid = :nid', array(':nid' => $edit['nid']))->fetchField();
+          $max = db_query('SELECT MAX(thread) FROM {comments} WHERE nid = :nid and pid = 0', array(':nid' => $edit['nid']))->fetchField();
           // Strip the "/" from the end of the thread.
           $max = rtrim($max, '/');
           // Finally, build the thread field for this new comment.