NULL Dates are translated to '0000-00-00' after upgrading to 1.2.2

Once the upgrade was done from Doctrine 1.2.1 to 1.2.2 we discovered that date related issues started to appear.
With dates that are persisted in DB as NULL are translated to "0000-00-00" when retrieved from DB. This has occurred in multiple places and is quite worrying as there is a lot of dates in our project. This means that everywhere in our codebase where we check a datevalue in our Models is NULL we need also to check for the string literal "0000-00-00".