Make CObjects mutable. Fixes #477441.
diff --git a/Misc/NEWS b/Misc/NEWS
index 967f93a..87a82e9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,8 @@
 Core and builtins
 -----------------
 
+- CObjects are now mutable (on the C level) through PyCObject_SetVoidPtr.
+
 - list.sort() now supports three keyword arguments:  cmp, key, and reverse.
   The key argument can be a function of one argument that extracts a
   comparison key from the original record:  mylist.sort(key=str.lower).