**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)
```
extern const Event ObsoleteReplicatedParts;
    extern const Event ReplicatedPartFetches;
    extern const Event DataAfterMergeDiffersFromReplica;
    extern const Event DataAfterMutationDiffersFromReplica;
    extern const Event CreatedLogEntryForMerge;
    extern const Event NotCreatedLogEntryForMerge;
    extern const Event CreatedLogEntryForMutation;
    extern const Event NotCreatedLogEntryForMutation;
}
namespace DB
{
namespace ErrorCodes
{
    extern const int CANNOT_READ_ALL_DATA;
    extern const int NOT_IMPLEMENTED;
    extern const int NO_ZOOKEEPER;
    extern const int INCORRECT_DATA;
    extern const int INCOMPATIBLE_COLUMNS;
    extern const int REPLICA_IS_ALREADY_EXIST;
    extern const int NO_REPLICA_HAS_PART;
    extern const int LOGICAL_ERROR;
    extern const int TOO_MANY_UNEXPECTED_DATA_PARTS;
    extern const int ABORTED;
    extern const int REPLICA_IS_NOT_IN_QUORUM;
    extern const int TABLE_IS_READ_ONLY;
    extern const int NOT_FOUND_NODE;
    extern const int NO_ACTIVE_REPLICAS;
    extern const int NOT_A_LEADER;
    extern const int TABLE_WAS_NOT_DROPPED;
    extern const int PARTITION_ALREADY_EXISTS;