Add an encoding property to TextIOBase instances.
Add sys.__std{in,out,err}__.
Make test_sys pass.
diff --git a/Lib/site.py b/Lib/site.py
index e00890e..f7ca83b 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -411,9 +411,9 @@
         def __new__(cls, *args, **kwds):
             return io.open(*args, **kwds)
     __builtin__.open = open
-    sys.stdin = io.open(0, "r")
-    sys.stdout = io.open(1, "w")
-    sys.stderr = io.open(2, "w")
+    sys.__stdin__ = sys.stdin = io.open(0, "r")
+    sys.__stdout__ = sys.stdout = io.open(1, "w")
+    sys.__stderr__ = sys.stderr = io.open(2, "w")
 
 
 def main():