**Describe the bug**
The ClickHouse client freezes when executing `ALTER TABLE` with `ADD COLUMN` and `MODIFY ORDER` on a table built using Replicated Versioned Collapsing Merge Tree engine.

**How to reproduce**
* ClickHouse client version 20.10.1.1.
Connecting to localhost:9000 as user default.
Connected to ClickHouse server version 20.10.1 revision 54440.

* `CREATE TABLE` statements
```
SHOW CREATE TABLE table0

┌─statement──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ CREATE TABLE default.table0
(
    `d` Date,
    `a` String,
    `b` UInt8,
    `x` String,
    `y` Int8,
    `version` UInt64,
    `sign` Int8 DEFAULT 1
)
ENGINE = ReplicatedVersionedCollapsingMergeTree('/clickhouse/tables/{shard}/table0', '{replica}', sign, version)
PARTITION BY y
ORDER BY d
SETTINGS index_granularity = 8192 │
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

1 rows in set. Elapsed: 0.004 sec.
```

* Queries to run that lead to unexpected result
```
ALTER TABLE table0 ADD COLUMN order UInt32, MODIFY ORDER BY (d, order)
```
break;
        }
    }
    if (!has_been_already_added)
    {
        const auto storage_settings_ptr = getSettings();
        String part_path = replica_path + "/parts/" + part_name;
        
        
        if (storage_settings_ptr->use_minimalistic_part_header_in_zookeeper)
        {
            ops.emplace_back(zkutil::makeCreateRequest(
                part_path, local_part_header.toString(), zkutil::CreateMode::Persistent));
        }
        else
        {
            ops.emplace_back(zkutil::makeCreateRequest(
                part_path, "", zkutil::CreateMode::Persistent));
            ops.emplace_back(zkutil::makeCreateRequest(
                part_path + "/columns", part->getColumns().toString(), zkutil::CreateMode::Persistent));
            ops.emplace_back(zkutil::makeCreateRequest(
                part_path + "/checksums", getChecksumsForZooKeeper(part->checksums), zkutil::CreateMode::Persistent));
        }
    }
    else
    {
        LOG_WARNING(log, "checkPartAndAddToZooKeeper: node {} already exists. Will not commit any nodes.", replica_path + "/parts/" + part_name);
    }
}
MergeTreeData::DataPartsVector StorageReplicatedMergeTree::checkPartChecksumsAndCommit(Transaction & transaction,