Fix crash in constant folding introduced by recent commit
Fix crash in constant folding introduced by recent commit

Graph::disconnect() actually modifies links, needs to create a copy to iterate
if disconnect happens form inside the loop.

Question tho whether we can control this somehow..

Reported by BzztPloink in IRC, thanks!

tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird