--- a/mercurial/changelog.py	Mon Feb 05 20:36:51 2018 +0100
+++ b/mercurial/changelog.py	Tue Feb 06 11:08:41 2018 +0100
@@ -90,6 +90,11 @@
         return self.offset
     def flush(self):
         pass
+
+    @property
+    def closed(self):
+        return self.fp.closed
+
     def close(self):
         self.fp.close()