hasKeyId returns wrong value

When creating a new object and then explicitly setting the primary key, hasKeyId returns the incorrect value.

$obj = new TestObj();
$obj->setKeyId(1);
var_dump($obj->hasKeyId()); // false, but should be true.

The impact appears to be minimal, however, because calling `save()` still produces an INSERT query.

It appears to have been introduced when the internal structure of modified fields changed.