Backport fixes to set objects:
rev 52964 sf 1576657 KeyError unpacks tuple arguments
rev 52963 sf 1456209 obscure resizing vulnerability
rev 52962 redundant calls to PyObject_Hash()
diff --git a/Misc/NEWS b/Misc/NEWS
index c9ca095..91e2bcf 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,12 +12,20 @@
Core and builtins
-----------------
+- Bug #1456209: In some obscure cases it was possible for a class with a
+ custom ``__eq__()`` method to confuse set internals when class instances
+ were used as a set's elements and the ``__eq__()`` method mutated the set.
+
+- Eliminated unnecessary repeated calls to hash() by set.intersection() and
+ set.symmetric_difference_update().
+
- Bug #1591996: Correctly forward exception in instance_contains().
- Bug #1588287: fix invalid assertion for `1,2` in debug builds.
- Bug #1576657: when setting a KeyError for a tuple key, make sure that
- the tuple isn't used as the "exception arguments tuple".
+ the tuple isn't used as the "exception arguments tuple". Applied to
+ both sets and dictionaries.
- Bug #1565514, SystemError not raised on too many nested blocks.