diff -r 9d06b65c5df2 -r 5e4f16874a9f mercurial/revlog.py
--- a/mercurial/revlog.py	Mon Oct 17 22:51:22 2016 -0700
+++ b/mercurial/revlog.py	Fri Oct 14 02:25:08 2016 +0200
@@ -297,7 +297,7 @@
             raise RevlogError(_("index %s unknown format %d")
                               % (self.indexfile, fmt))
 
-        self._storedeltachains = True
+        self.storedeltachains = True
 
         self._io = revlogio()
         if self.version == REVLOGV0:
@@ -1471,7 +1471,7 @@
             textlen = len(text)
 
         # should we try to build a delta?
-        if prev != nullrev and self._storedeltachains:
+        if prev != nullrev and self.storedeltachains:
             tested = set()
             # This condition is true most of the time when processing
             # changegroup data into a generaldelta repo. The only time it