Issue 2235: __hash__ is once again inherited by default, but inheritance can be blocked explicitly so that collections.Hashable remains meaningful
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 39465f3..fbbdf6e 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -2109,7 +2109,7 @@
&set_as_number, /* tp_as_number */
&set_as_sequence, /* tp_as_sequence */
0, /* tp_as_mapping */
- 0, /* tp_hash */
+ (hashfunc)PyObject_HashNotImplemented, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */