diff -r 6ceb3c4c3ab6 -r f80d9ddc40f3 mercurial/pure/osutil.py
--- a/mercurial/pure/osutil.py	Sun Mar 26 17:12:06 2017 +0900
+++ b/mercurial/pure/osutil.py	Sun Mar 26 16:33:12 2017 +0900
@@ -342,8 +342,8 @@
             # unfortunately, f.name is '<fdopen>' at this point -- so we store
             # the name on this wrapper. We cannot just assign to f.name,
             # because that attribute is read-only.
-            object.__setattr__(self, 'name', name)
-            object.__setattr__(self, '_file', f)
+            object.__setattr__(self, r'name', name)
+            object.__setattr__(self, r'_file', f)
 
         def __iter__(self):
             return self._file