Use __stdin__ instead of stdin to derive FileType -- safer against
assignments.
diff --git a/Lib/types.py b/Lib/types.py
index c440a5c..70e624a 100644
--- a/Lib/types.py
+++ b/Lib/types.py
@@ -42,7 +42,7 @@
 ModuleType = type(sys)
 
 try:
-    FileType = type(sys.stdin)          # XXX what if it was assigned to?
+    FileType = type(sys.__stdin__)
 except:
     pass
 XRangeType = type(xrange(0))