--- a/mercurial/byterange.py	Sat Sep 30 07:42:59 2017 -0400
+++ b/mercurial/byterange.py	Sat Sep 30 07:43:11 2017 -0400
@@ -44,7 +44,6 @@
 
 class RangeError(IOError):
     """Error raised when an unsatisfiable range is requested."""
-    pass
 
 class HTTPRangeHandler(urlreq.basehandler):
     """Handler that enables HTTP Range headers.