**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)
```
}
    }
    if (getSettings()->detach_old_local_parts_when_cloning_replica)
    {
        auto metadata_snapshot = getInMemoryMetadataPtr();
        for (const auto & part : parts_to_remove_from_working_set)
        {
            LOG_INFO(log, "Detaching {}", part->relative_path);
            part->makeCloneInDetached("clone", metadata_snapshot);
        }
    }
    removePartsFromWorkingSet(parts_to_remove_from_working_set, true);
    for (const String & name : active_parts)
    {
        LogEntry log_entry;
        log_entry.type = LogEntry::GET_PART;
        log_entry.source_replica = "";
        log_entry.new_part_name = name;
        log_entry.create_time = tryGetPartCreateTime(zookeeper, source_path, name);
        zookeeper->create(replica_path + "/queue/queue-", log_entry.toString(), zkutil::CreateMode::PersistentSequential);
    }
    LOG_DEBUG(log, "Queued {} parts to be fetched", active_parts.size());
    
    for (const String & entry : source_queue)
    {
        zookeeper->create(replica_path + "/queue/queue-", entry, zkutil::CreateMode::PersistentSequential);
    }
    LOG_DEBUG(log, "Copied {} queue entries", source_queue.size());
}
void StorageReplicatedMergeTree::cloneReplicaIfNeeded(zkutil::ZooKeeperPtr zookeeper)