Comment 2 for bug 378616

Well... isn't this because it now supports timezone naive datetimes? In which case the new behaviour makes sense?
In any case I think it's a bad idea to have this a configuration setting. You'll change the way othe peoples software behaves. A parameter is better in that case.

I also think fiddling with DateTime is a generally bad idea. DateTime is a dead end, we should only change it if it has proper bugs, not because we want a different type of behaviour.