diff -r 9f35c7836f60 -r 67026d65a4fc mercurial/changelog.py
--- a/mercurial/changelog.py	Wed May 17 20:01:29 2017 -0700
+++ b/mercurial/changelog.py	Wed May 17 19:52:18 2017 -0700
@@ -279,7 +279,7 @@
 
         if self._initempty:
             # changelogs don't benefit from generaldelta
-            self.version &= ~revlog.REVLOGGENERALDELTA
+            self.version &= ~revlog.FLAG_GENERALDELTA
             self._generaldelta = False
 
         # Delta chains for changelogs tend to be very small because entries