RebuildNode(const std::string &ref,
             const CurrentStack &currstack) :
     verref(ref),
     buildindex(-1),
     rebuild(false)
 {
   if (currstack.size()) {
     users.insert(currstack.back());
   }
 }
 void AddUser(const CurrentStack &currstack) {
   if (currstack.size()) {
     users.insert(currstack.back());
   }
 }