diff -r 120ecb17242b -r 328557af18eb mercurial/context.py
--- a/mercurial/context.py	Sat Dec 15 14:55:06 2018 -0500
+++ b/mercurial/context.py	Sun Dec 16 17:08:46 2018 +0900
@@ -2292,6 +2292,9 @@
         if copied:
             self._copied = (copied, nullid)
 
+    def cmp(self, fctx):
+        return self.data() != fctx.data()
+
     def data(self):
         return self._data