diff -r b41d023a412a -r 0a5b20c107a6 mercurial/changelog.py
--- a/mercurial/changelog.py	Thu Aug 09 16:02:14 2018 -0700
+++ b/mercurial/changelog.py	Thu Aug 09 16:11:24 2018 -0700
@@ -303,7 +303,7 @@
         # Delta chains for changelogs tend to be very small because entries
         # tend to be small and don't delta well with each. So disable delta
         # chains.
-        self.storedeltachains = False
+        self._storedeltachains = False
 
         self._realopener = opener
         self._delayed = False