pep-0455: Update status.

pep-0455.txt

@@ -4,7 +4,7 @@ Version: $Revision$
 Last-Modified: $Date$
 Author: Antoine Pitrou <solipsis@pitrou.net>
 BDFL-Delegate: Raymond Hettinger
-Status: Draft
+Status: Rejected
 Type: Standards Track
 Content-Type: text/x-rst
 Created: 13-Sep-2013
@@ -20,6 +20,11 @@ called "TransformDict" in this PEP.  This structure is a mutable mapping
 which transforms the key using a given function when doing a lookup, but
 retains the original key when reading.
 
+Rejection
+---------
+
+See https://mail.python.org/pipermail/python-dev/2015-May/140003.html
+
 
 Rationale
 =========