version 21.5.5.12 (official build)

I'm trying to change data type for a column that is used in the TTL expression.
It works well when the table is empty.
When the table is not empty, the mutation fails.
As a result the table ends up in an inconsistent state.

```
create table test
(
InsertionDateTime DateTime,
TTLDays Int32 DEFAULT CAST(365, 'Int32')
)
Engine=MergeTree()
order by tuple()
TTL InsertionDateTime + toIntervalDay(TTLDays);

Ok.

insert into test values (now(), 23);

Ok.

ALTER TABLE test modify column TTLDays Int16 DEFAULT CAST(365, 'Int16');

Code: 341, e.displayText() = DB::Exception: Exception happened during execution of mutation 'mutation_2.txt' with part 'all_1_1_0' reason: 'Code: 10, e.displayText() = DB::Exception: Not found column InsertionDateTime in block. There are only columns: TTLDays (version 21.5.5.12 (official build))'. This error maybe retryable or not. In case of unretryable error, mutation can be killed with KILL MUTATION query (version 21.5.5.12 (official build)) [DB Errorcode=341]

insert into test values (now(), 23);

Ok.

select table, column, type, sum(rows) rows, sum(column_bytes_on_disk) on_disk
from system.parts_columns where column like 'TTLDays'
group by database, table, column, type

table | column  | type  | rows | on_disk
------+---------+-------+------+--------
test  | TTLDays | Int32 |    1 |      86
test  | TTLDays | Int16 |    1 |      84
```
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;