small fix in the upper bound change computation in Prunable
small fix in the upper bound change computation in Prunable

stereomatchingkiss/mlpack,bmswgnp/mlpack,bmswgnp/mlpack,minhpqn/mlpack,erubboli/mlpack,ranjan1990/mlpack,trungda/mlpack,theranger/mlpack,ajjl/mlpack,chenmoshushi/mlpack,theranger/mlpack,BookChan/mlpack,bmswgnp/mlpack,stereomatchingkiss/mlpack,minhpqn/mlpack,datachand/mlpack,thirdwing/mlpack,Azizou/mlpack,ersanliqiao/mlpack,BookChan/mlpack,chenmoshushi/mlpack,ersanliqiao/mlpack,ersanliqiao/mlpack,lezorich/mlpack,thirdwing/mlpack,ranjan1990/mlpack,erubboli/mlpack,palashahuja/mlpack,lezorich/mlpack,lezorich/mlpack,erubboli/mlpack,theranger/mlpack,palashahuja/mlpack,minhpqn/mlpack,trungda/mlpack,stereomatchingkiss/mlpack,darcyliu/mlpack,datachand/mlpack,ajjl/mlpack,darcyliu/mlpack,thirdwing/mlpack,Azizou/mlpack,trungda/mlpack,datachand/mlpack,ranjan1990/mlpack,palashahuja/mlpack,BookChan/mlpack,Azizou/mlpack,darcyliu/mlpack,chenmoshushi/mlpack,ajjl/mlpack