fix some distribution test cases
fix some distribution test cases

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