Make sure to intern attribute string in PyObject_SetAttr.

src/capi/object.cpp

@@ -445,12 +445,15 @@ extern "C" int PyObject_SetAttr(PyObject* obj, PyObject* name, PyObject* value)
         }
     }
 
+    BoxedString* name_str = static_cast<BoxedString*>(name);
+    internStringMortalInplace(name_str);
+
     assert(PyString_Check(name));
     try {
         if (value == NULL)
-            delattr(obj, static_cast<BoxedString*>(name));
+            delattr(obj, name_str);
         else
-            setattr(obj, static_cast<BoxedString*>(name), value);
+            setattr(obj, name_str, value);
     } catch (ExcInfo e) {
         setCAPIException(e);
         return -1;

test/tests/exceptions_basic.py

@@ -101,3 +101,12 @@ def f14():
     except Exception:
         pass
 f14()
+
+def test_set_state():
+    exc = BaseException()
+    print exc.__dict__
+    attrs = {"x": 1, "y": 2}
+    exc.__setstate__(attrs)
+    print exc.__dict__ == attrs
+
+test_set_state()