--- a/mercurial/revlog.py	Tue Nov 11 21:39:56 2014 -0800
+++ b/mercurial/revlog.py	Tue Nov 11 21:41:12 2014 -0800
@@ -1254,7 +1254,7 @@
                                         cachedelta[1])
         else:
             textlen = len(text)
-        if (d is None or dist > textlen * 2 or
+        if (d is None or dist > textlen * 2 or l > textlen or
             (self._maxchainlen and chainlen > self._maxchainlen)):
             text = buildtext()
             data = self.compress(text)