Restore comment

Author: nascheme

Objects/typeobject.c

@@ -5891,6 +5891,9 @@ _PyType_LookupStackRefAndVersion(PyTypeObject *type, PyObject *name, _PyStackRef
     /* We may end up clearing live exceptions below, so make sure it's ours. */
     assert(!PyErr_Occurred());
 
+    // We need to atomically do the lookup and capture the version before
+    // anyone else can modify our mro or mutate the type.
+
     PyObject *res;
     int error;
     unsigned int assigned_version = 0; // 0 is not a valid version