prevent abuse in clan wars

It has happened several times now that participants in clans wars leave and later on return to the clan. I found out why most of them do it.
They gone get some troops for their castle in another clan an then return ( not available in there own clan) to do an attack. I consider this as foul play. I believe that when you leave a clan war you must be prevented do join in again. Just to make sure there is no abuse, call it disqualified.

I strong believe in fair play clan wars but lot's of others love to misbehave....shame on them!

I actually strongly agree with this. If your clan can't supply it then you can't use it in the war..... that's only fair since it is your clan against another. And i find that this will also reduce the chance of spying.