Shopping cart: Unable to calculate assignment conflicts

This is tricky thing that forbids our end customer to fully use sponsored improvement of transfering role ownership from one user to another.

Endusers get warning message in the shopping cart, since they dont have #read or #get autz on the target user assignments field. That is correct. However, end users do not really need such authorization to simply request (#assign) roles for anybody else, as long as selected roles do not contain any exlusion policy rule. And this is the case. On top of that, requested roles are in relation=owner,approver and Im not sure if we even support exclusions here.