Bug #1648179:  set.update() not recognizing __iter__ overrides in dict subclasses.
diff --git a/Misc/NEWS b/Misc/NEWS
index ff8a082..303f4cf 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -16,6 +16,9 @@
   a weakref on itself during a __del__ call for new-style classes (classic
   classes still have the bug).
 
+- Bug #1648179:  set.update() did not recognize an overridden __iter__ 
+  method in subclasses of dict.
+
 - Bug #1579370: Make PyTraceBack_Here use the current thread, not the
   frame's thread state.