No need to import sys.  (Andrew Dalke & kjpylint)
diff --git a/Lib/pty.py b/Lib/pty.py
index 53a4b2d..2ba1938 100644
--- a/Lib/pty.py
+++ b/Lib/pty.py
@@ -7,7 +7,7 @@
 # Author: Steen Lumholt -- with additions by Guido.
 
 from select import select
-import os, sys, FCNTL
+import os, FCNTL
 import tty
 
 STDIN_FILENO = 0