Thanks - this is a bug which has been around for a while - well caught!
To fix it, change the following line in qa-db-selects.php:
" LEFT JOIN ^userpoints AS edituserpoints ON editposts.userid=edituserpoints.userid".
... to ...
" LEFT JOIN ^userpoints AS edituserpoints ON editposts.lastuserid=edituserpoints.userid".
This fix will also be rolled into the 1.4 beta. Thanks again.