Issue #5640: Fix _multibytecodec so that CJK codecs don't repeat
error replacement returned by codec error callbacks twice in
IncrementalEncoder and StreamWriter.
diff --git a/Misc/NEWS b/Misc/NEWS
index 8e9fbf4..c7b203d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -58,6 +58,10 @@
 Library
 -------
 
+- Issue #5640: Fix _multibytecodec so that CJK codecs don't repeat
+  error substitutions from non-strict codec error callbacks in
+  incrementalencoder and StreamWriter.
+
 - Issue #5656: Fix the coverage reporting when running the test suite with
   the -T argument.