Add -3 warnings that set.copy(), dict.copy(), and defaultdict.copy() will go away in Py3.x
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index eaa490e..165221e 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1528,6 +1528,10 @@
 static PyObject *
 dict_copy(register PyDictObject *mp)
 {
+	if (Py_Py3kWarningFlag &&
+	    PyErr_Warn(PyExc_DeprecationWarning, 
+		       "dict.copy() not supported in 3.x") < 0)
+		return NULL;
 	return PyDict_Copy((PyObject*)mp);
 }