--- a/mercurial/revlog.py	Wed Oct 03 16:50:32 2007 -0500
+++ b/mercurial/revlog.py	Wed Oct 03 17:17:27 2007 -0500
@@ -1087,9 +1087,13 @@
             if infocollect is not None:
                 infocollect(nb)
 
-            d = self.revdiff(a, b)
             p = self.parents(nb)
             meta = nb + p[0] + p[1] + lookup(nb)
+            if a == -1:
+                d = self.revision(nb)
+                meta += mdiff.trivialdiffheader(len(d))
+            else:
+                d = self.revdiff(a, b)
             yield changegroup.genchunk("%s%s" % (meta, d))
 
         yield changegroup.closechunk()