**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)
```
updateQuorum(part_name, false);
            }
            
            if (part_info.level != 0 || part_info.mutation != 0)
            {
                Strings quorum_parts = zookeeper->getChildren(zookeeper_path + "/quorum/parallel");
                for (const String & quorum_part : quorum_parts)
                {
                    auto quorum_part_info = MergeTreePartInfo::fromPartName(quorum_part, format_version);
                    if (part_info.contains(quorum_part_info))
                        updateQuorum(quorum_part, true);
                }
            }
            merge_selecting_task->schedule();
            for (const auto & replaced_part : replaced_parts)
            {
                LOG_DEBUG(log, "Part {} is rendered obsolete by fetching part {}", replaced_part->name, part_name);
                ProfileEvents::increment(ProfileEvents::ObsoleteReplicatedParts);
            }
            write_part_log({});
        }
        else
        {
            
            part->is_temp = false;
            part->renameTo("detached/" + part_name, true);
        }
    }
    catch (const Exception & e)
    {