diff -r 0c0bfea3f72a -r 16276b1c0658 mercurial/revlog.py
--- a/mercurial/revlog.py	Wed May 31 19:41:01 2006 +0200
+++ b/mercurial/revlog.py	Wed May 31 22:25:20 2006 +0200
@@ -1196,8 +1196,6 @@
             start = self.start(base)
             end = self.end(t)
 
-        if node is None:
-            raise RevlogError(_("group to be added is empty"))
         return node
 
     def strip(self, rev, minlink):