Fixed issue #4233.
Changed semantic of _fileio.FileIO's close()  method on file objects with closefd=False. The file descriptor is still kept open but the file object behaves like a closed file. The FileIO  object also got a new readonly attribute closefd.
Approved by Barry
diff --git a/Misc/NEWS b/Misc/NEWS
index 7de0685..f17e758 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,6 +15,11 @@
 Core and Builtins
 -----------------
 
+- Issue #4233: Changed semantic of ``_fileio.FileIO``'s ``close()`` 
+  method on file objects with closefd=False. The file descriptor is still
+  kept open but the file object behaves like a closed file. The ``FileIO``
+  object also got a new readonly attribute ``closefd``.
+
 - Issue #3626: On cygwin, starting python with a non-existent script name
   would not display anything if the file name is only 1 character long.