diff -r 726dd73df3b9 -r ed04d7254a91 mercurial/util.py
--- a/mercurial/util.py	Sun Aug 13 15:20:16 2017 +0900
+++ b/mercurial/util.py	Tue Aug 15 19:27:24 2017 +0900
@@ -3752,6 +3752,8 @@
 
         value = docobject()
         value.__doc__ = doc
+        value._origdoc = engine.bundletype.__doc__
+        value._origfunc = engine.bundletype
 
         items[bt[0]] = value