And waits for them. That's pointless.
Block updated_header;
    std::unique_ptr<MutationsInterpreter> interpreter;
    const auto data_settings = data.getSettings();
    MutationCommands for_interpreter;
    MutationCommands for_file_renames;
    splitMutationCommands(source_part, commands_for_part, for_interpreter, for_file_renames);
    UInt64 watch_prev_elapsed = 0;
    MergeStageProgress stage_progress(1.0);
    NamesAndTypesList storage_columns = metadata_snapshot->getColumns().getAllPhysical();
    NameSet materialized_indices;
    NameSet materialized_projections;
    MutationsInterpreter::MutationKind::MutationKindEnum mutation_kind
        = MutationsInterpreter::MutationKind::MutationKindEnum::MUTATE_UNKNOWN;
    if (!for_interpreter.empty())
    {
        interpreter = std::make_unique<MutationsInterpreter>(
            storage_from_source_part, metadata_snapshot, for_interpreter, context_for_reading, true);
        materialized_indices = interpreter->grabMaterializedIndices();
        materialized_projections = interpreter->grabMaterializedProjections();
        mutation_kind = interpreter->getMutationKind();
        in = interpreter->execute();
        updated_header = interpreter->getUpdatedHeader();
        in->setProgressCallback(MergeProgressCallback(merge_entry, watch_prev_elapsed, stage_progress));
    }
    auto single_disk_volume = std::make_shared<SingleDiskVolume>("volume_" + future_part.name, space_reservation->getDisk(), 0);
    auto new_data_part = data.createPart(
        future_part.name, future_part.type, future_part.part_info, single_disk_volume, "tmp_mut_" + future_part.name);
    new_data_part->uuid = future_part.uuid;
    new_data_part->is_temp = true;
    new_data_part->ttl_infos = source_part->ttl_infos;