Notnull validator no longer checks for empty strings

lib/Doctrine/Validator/Notnull.php

@@ -40,9 +40,6 @@ class Doctrine_Validator_Notnull
      */
     public function validate(Doctrine_Record $record, $key, $value)
     {
-        if ($value === null || $value === '') {
-            return false;
-        }
-        return true;
+        return !is_null($value);
     }
 }