bnb_search as implemented @achow101 does not terminate once an optimal search is found. This behavior is evident I believe when inspecting the test which sets the target to 5 and uses the utxo pool 4,3,2,1. since combinations of 4 are evaluated first, the bnb_search finds an optimal solution of 4,1. However, instead of terminating when the best_waste = 0 (no better solution can be found), the search continues and instead finds another solution 2,3 which also has a best_waste = 0. Why not terminate once an optimal solution is found instead of continuing to search?
