diff -r 31a5973fcf96 -r 85c82ebc96a3 mercurial/changelog.py
--- a/mercurial/changelog.py	Mon May 16 12:44:34 2011 +0200
+++ b/mercurial/changelog.py	Mon May 16 13:06:48 2011 +0200
@@ -100,6 +100,10 @@
 class changelog(revlog.revlog):
     def __init__(self, opener):
         revlog.revlog.__init__(self, opener, "00changelog.i")
+        if self._initempty:
+            # changelogs don't benefit from generaldelta
+            self.version &= ~revlog.REVLOGGENERALDELTA
+            self._generaldelta = False
         self._realopener = opener
         self._delayed = False
         self._divert = False