**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)
```
for (PartDescriptionPtr & part_desc : final_parts)
        obtain_part(part_desc);
    MutableDataPartsVector res_parts;
    for (PartDescriptionPtr & part_desc : final_parts)
        res_parts.emplace_back(part_desc->res_part);
    try
    {
        
        auto zookeeper = getZooKeeper();
        Transaction transaction(*this);
        Coordination::Requests ops;
        for (PartDescriptionPtr & part_desc : final_parts)
        {
            renameTempPartAndReplace(part_desc->res_part, nullptr, &transaction);
            getCommitPartOps(ops, part_desc->res_part);
            if (ops.size() > zkutil::MULTI_BATCH_SIZE)
            {
                zookeeper->multi(ops);
                ops.clear();
            }
        }
        if (!ops.empty())
            zookeeper->multi(ops);
        {
            auto data_parts_lock = lockParts();
            transaction.commit(&data_parts_lock);
            if (replace)
                parts_to_remove = removePartsInRangeFromWorkingSet(drop_range, true, false, data_parts_lock);
        }