Fix custom tuple subclasses

src/runtime/set.cpp

@@ -493,6 +493,7 @@ Box* setUnion(BoxedSet* self, BoxedTuple* args) {
 
 static void _setDifferenceUpdate(BoxedSet* self, BoxedTuple* args) {
     for (auto container : args->pyElements()) {
+        AUTO_DECREF(container);
         if (PyAnySet_Check(container)) {
             for (auto&& elt : ((BoxedSet*)container)->s) {
                 _setRemove(self, elt);

src/runtime/tuple.cpp

@@ -382,10 +382,19 @@ extern "C" Box* tupleNew(Box* _cls, BoxedTuple* args, BoxedDict* kwargs) {
         }
 
         std::vector<Box*> elts;
-        for (auto e : elements->pyElements())
-            elts.push_back(e);
+        try {
+            for (auto e : elements->pyElements())
+                elts.push_back(e);
+        } catch (ExcInfo e) {
+            for (auto e : elts)
+                Py_DECREF(e);
+            throw e;
+        }
 
-        return BoxedTuple::create(elts.size(), &elts[0], cls);
+        auto rtn = BoxedTuple::create(elts.size(), cls);
+        memcpy(&rtn->elts[0], &elts[0], elts.size() * sizeof(Box*));
+
+        return rtn;
     } else {
         if (cls == tuple_cls)
             return incref(EmptyTuple);

test/tests/defaults_changing.py

-# expected: reffail
-
 def func(a, b=1):
     print a, b
 func(0)