anchor.diff:                          case bitcask:open(filename:join(DataRoot, DataFile),
                                             ReadOpts) of
                               Ref1 when is_reference(Ref1) ->
  -                                bitcask:fold_keys(Ref1, FoldFun, Acc);
  +                                FoldResults =
  +                                    bitcask:fold_keys(Ref1, FoldFun, Acc),
  +                                bitcask:close(Ref1),
  +                                FoldResults;
                               {error, Reason} ->
                                   {error, Reason}
                           end
  
positive.code:                         case bitcask:open(filename:join(DataRoot, DataFile),
                                            ReadOpts) of
                              Ref1 when is_reference(Ref1) ->
                                  bitcask:fold(Ref1, FoldFun, Acc);
                              {error, Reason} ->
                                  {error, Reason}
                          end
  
negative.code:                                     bitcask:fold_keys(Ref1,
                                                        FoldFun,
                                                        {Acc, sets:new()}),
                                  bitcask:close(Ref1),
                                  Acc1;
                              {error, Reason} ->
                                  {error, Reason}
  