Comment #23 on issue 586 by cy.delau...(a)gmail.com: Compute invocation
candidates with different strategies seems to be broken
http://code.google.com/p/moose-technology/issues/detail?id=586
I don't know what is the problem, I just put a '^self' when encountering
problematic case (the empty collection). Like my previous change , I think
it does not break anything, but just let RoelTyper less precise for some
cases (that are not working)