Avoid failing on current mypy master

ilevkivskyi · web-flow · commit 60135379fdcb · 2017-04-25T18:19:20.000+02:00
diff --git a/stdlib/3/typing.pyi b/stdlib/3/typing.pyi
@@ -17,7 +17,7 @@ Type = object()
 _promote = object()
 no_type_check = object()
 ClassVar = object()
-Protocol = object()
+class Protocol: pass
 
 class GenericMeta(type): ...
 
