Believe the datablocks predictor when determining if data on a node gets
stored internal or not. Also make a note that the datablocks predictor takes
NO extended attributes stored in the node into account

In rare cases it could lead to confusion where the predictor would say it
wouldn't fit internally when it could just have fitted. This would trigger the
assertion. Now it will on rare accasions create a datablock even though it
might have fitted.

(reinoud)