this law is now obsolete. the criteria is now if the referee considers the goalkeeper to have had hold of the ball foe an excessive amount of time, then the referee would penalise with an indirect free kick
So why do the current, 2016-17 laws, state the following ...
An indirect free kick is awarded if a goalkeeper, inside their penalty area, commits any of the following offences:
• controls the ball with the hands for more than six seconds before releasing it