Fix variants of deque.extend:  d.extend(d)   d+=d  d.extendleft(d)
diff --git a/Misc/NEWS b/Misc/NEWS
index b99dbef..8f051b7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -159,6 +159,8 @@
 
 - Add a reverse() method to collections.deque().
 
+- Fix variations of extending deques:  d.extend(d)  d.extendleft(d)  d+=d
+
 - Issue #6986: Fix crash in the JSON C accelerator when called with the
   wrong parameter types.  Patch by Victor Stinner.