anchor.diff:  
                          rebalance(KeepNodes, EjectNodes, FailedNodes,
                                    BucketConfigs,
  -                                 DeltaNodes, DeltaRecoveryBucketTuples)
  +                                 DeltaNodes, DeltaRecoveryBucketTuples);
  +                   {error, not_possible} ->
  +                       proc_lib:init_ack({error, delta_recovery_not_possible})
                  end
          end, []]).
   
  
positive.code:                      || {Bucket, BucketConfig} <- AllBucketConfigs,
                          proplists:get_value(type, BucketConfig) =:= membase],
  
      Recovered0 = build_delta_recovery_buckets_loop(MappedConfigs, DeltaRecoveryBuckets, []),
  
      [{Bucket,
        build_transitional_bucket_config(BucketConfig, Map, Opts, DeltaNodes),
        {Map, Opts}}
       || {Bucket, BucketConfig, {Map, Opts}} <- Recovered0].
  
  build_delta_recovery_buckets_loop([] = _MappedConfigs, _DeltaRecoveryBuckets, Acc) ->
      Acc;
  build_delta_recovery_buckets_loop(MappedConfigs, DeltaRecoveryBuckets, Acc) ->
      [{Bucket, BucketConfig, RecoverResult0} | RestMapped] = MappedConfigs,
  
  
negative.code:                     ?rebalance_debug("Couldn't delta recover bucket ~s when we care about delta recovery of that bucket", [Bucket]),
                      %% run rest of elements for logging
                      _ = build_delta_recovery_buckets_loop(RestMapped, DeltaRecoveryBuckets, []),
                      {error, not_possible};
                  false ->
                      build_delta_recovery_buckets_loop(RestMapped, DeltaRecoveryBuckets, Acc)
              end
  