Merge from 3.1.

The fix was already committed to 3.2, but I merged two small changes
recommended by Raymond while I was working on the 2.7 patch to ease
future merges.

diff --cc Objects/setobject.c
index 478b5cb651dec520e92ead08c79c8aedc785bad2,7aa1a7faee3a4d91ad77e5161c6680f87d422a65..48edad8a31a32547773f2d567e2a0ef2c84aec4e
--- 1/Objects/setobject.c
--- 2/Objects/setobject.c
+++ b/Objects/setobject.c
@@@ -365,6 -365,7 +365,7 @@@ set_add_entry(register PySetObject *so
  {
      register Py_ssize_t n_used;
      PyObject *key = entry->key;
 -    long hash = entry->hash;
++    Py_hash_t hash = entry->hash;
  
      assert(so->fill <= so->mask);  /* at least one empty slot */
      n_used = so->used;
@@@ -639,6 -640,7 +640,7 @@@ set_merge(PySetObject *so, PyObject *ot
  {
      PySetObject *other;
      PyObject *key;
 -    long hash;
++    Py_hash_t hash;
      register Py_ssize_t i;
      register setentry *entry;