**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)
```
ops.push_back(zkutil::makeCreateRequest(partition_path, "", zkutil::CreateMode::Persistent));
        
        
        
        ops.push_back(zkutil::makeSetRequest(block_numbers_path, "", -1));
        Coordination::Responses responses;
        Coordination::Error code = zookeeper->tryMulti(ops, responses);
        if (code != Coordination::Error::ZOK && code != Coordination::Error::ZNODEEXISTS)
            zkutil::KeeperMultiException::check(code, ops, responses);
    }
    EphemeralLockInZooKeeper lock;
    
    try
    {
        lock = EphemeralLockInZooKeeper(
            partition_path + "/block-", zookeeper_path + "/temp", *zookeeper, &deduplication_check_ops);
    }
    catch (const zkutil::KeeperMultiException & e)
    {
        if (e.code == Coordination::Error::ZNODEEXISTS && e.getPathForFirstFailedOp() == zookeeper_block_id_path)
            return {};
        throw Exception("Cannot allocate block number in ZooKeeper: " + e.displayText(), ErrorCodes::KEEPER_EXCEPTION);
    }
    catch (const Coordination::Exception & e)
    {
        throw Exception("Cannot allocate block number in ZooKeeper: " + e.displayText(), ErrorCodes::KEEPER_EXCEPTION);
    }
    return {std::move(lock)};
}
Strings StorageReplicatedMergeTree::waitForAllReplicasToProcessLogEntry(