Support unicode names

Objects/weakrefobject.c

@@ -166,8 +166,8 @@ weakref_repr(PyWeakReference *self)
 						   "__name__");
 	if (nameobj == NULL)
 		PyErr_Clear();
-	else if (PyString_Check(nameobj))
-		name = PyString_AS_STRING(nameobj);
+	else if (PyUnicode_Check(nameobj))
+		name = PyUnicode_AsString(nameobj);
         PyOS_snprintf(buffer, sizeof(buffer),
 		      name ? "<weakref at %p; to '%.50s' at %p (%s)>"
 		           : "<weakref at %p; to '%.50s' at %p>",