anchor.diff:                    end
             end, []),
   
  -    lists:usort(BucketDbs).
  +    BucketDbs2 = [D || D <- couch_server:all_known_databases(),
  +                       Pred(D)],
  +
  +    lists:umerge(lists:usort(BucketDbs),
  +                 lists:usort(BucketDbs2)).
   
   delete_couch_database(DB) ->
       RV = couch_server:delete(DB, []),
  
positive.code:     N = byte_size(Prefix),
  
      fun (DbName) ->
              try
                  ActualPrefix = binary:part(DbName, 0, N),
                  ActualPrefix =:= Prefix
              catch
                  %% can happen when DbName is shorter than expected prefix
                  error:badarg ->
                      false
              end
      end.
  
negative.code: 
  delete_databases_and_files(Bucket) ->
      AllDBs = bucket_databases(Bucket),
      MasterDB = iolist_to_binary([Bucket, <<"/master">>]),
      {MaybeMasterDb, RestDBs} = lists:partition(
                              fun (Name) ->
                                      Name =:= MasterDB
                              end, AllDBs),
      case delete_databases_loop(MaybeMasterDb ++ RestDBs) of
          ok ->
  