Add a final permutation step to the tuple hash function.

Prevents a collision pattern that occurs with nested tuples.
(Yitz Gale provided code that repeatably demonstrated the weakness.)

1 files changed, 1 insertions, 0 deletions

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index ff20b43..ea7d753 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -280,6 +280,7 @@ tuplehash(PyTupleObject *v)
 		x = (x ^ y) * mult;
 		mult += 82520L + len + len;
 	}
+	x += 97531L;
 	if (x == -1)
 		x = -2;
 	return x;