**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)
```
const StoragePtr & source_table, const ASTPtr & partition, bool replace, const Context & context)
{
    
    auto lock1 = lockForShare(context.getCurrentQueryId(), context.getSettingsRef().lock_acquire_timeout);
    auto lock2 = source_table->lockForShare(context.getCurrentQueryId(), context.getSettingsRef().lock_acquire_timeout);
    auto source_metadata_snapshot = source_table->getInMemoryMetadataPtr();
    auto metadata_snapshot = getInMemoryMetadataPtr();
    Stopwatch watch;
    MergeTreeData & src_data = checkStructureAndGetMergeTreeData(source_table, source_metadata_snapshot, metadata_snapshot);
    String partition_id = getPartitionIDFromQuery(partition, context);
    DataPartsVector src_all_parts = src_data.getDataPartsVectorInPartition(MergeTreeDataPartState::Committed, partition_id);
    DataPartsVector src_parts;
    MutableDataPartsVector dst_parts;
    Strings block_id_paths;
    Strings part_checksums;
    std::vector<EphemeralLockInZooKeeper> ephemeral_locks;
    LOG_DEBUG(log, "Cloning {} parts", src_all_parts.size());
    static const String TMP_PREFIX = "tmp_replace_from_";
    auto zookeeper = getZooKeeper();