**Describe the bug**
```
5828589:2021.04.27 03:13:08.824665 [ 6101 ] {} <Trace> test_27.concurrent_alter_add_drop_3 (825021f7-129f-4841-ad6b-92215e3f1a94): Renaming temporary part tmp_merge_all_0_4_7_17 to all_0_4_7_17.
5828590:2021.04.27 03:13:08.824778 [ 3358 ] {} <Trace> test_27.concurrent_alter_add_drop_2 (f0a064d0-dc89-4710-9781-a49bb0c16461): Renaming temporary part tmp_merge_all_0_4_7_17 to all_0_4_7_17.
5828591:2021.04.27 03:13:08.824823 [ 6101 ] {} <Warning> test_27.concurrent_alter_add_drop_3 (825021f7-129f-4841-ad6b-92215e3f1a94): Tried to add obsolete part all_0_4_7_17 covered by all_0_4_13_34 (state Committed)
5828623:2021.04.27 03:13:08.824951 [ 3358 ] {} <Warning> test_27.concurrent_alter_add_drop_2 (f0a064d0-dc89-4710-9781-a49bb0c16461): Tried to add obsolete part all_0_4_7_17 covered by all_0_4_13_34 (state Committed)
5828624:2021.04.27 03:13:08.824995 [ 6101 ] {} <Warning> test_27.concurrent_alter_add_drop_3 (825021f7-129f-4841-ad6b-92215e3f1a94) (MergerMutator): Unexpected number of parts removed when adding all_0_4_7_17: 0 instead of 1
5828625:2021.04.27 03:13:08.825147 [ 3358 ] {} <Warning> test_27.concurrent_alter_add_drop_2 (f0a064d0-dc89-4710-9781-a49bb0c16461) (MergerMutator): Unexpected number of parts removed when adding all_0_4_7_17: 0 instead of 1
5828643:2021.04.27 03:13:08.831273 [ 3358 ] {} <Trace> test_27.concurrent_alter_add_drop_2 (f0a064d0-dc89-4710-9781-a49bb0c16461): Trying to immediately remove part all_0_4_7_17 (state Temporary)
5828644:2021.04.27 03:13:08.831658 [ 3358 ] {} <Fatal> : Logical error: 'Part all_0_4_7_17 doesn't exist'.
5828648:2021.04.27 03:13:08.832767 [ 6101 ] {} <Trace> test_27.concurrent_alter_add_drop_3 (825021f7-129f-4841-ad6b-92215e3f1a94): Trying to immediately remove part all_0_4_7_17 (state Temporary)
5828649:2021.04.27 03:13:08.833210 [ 6101 ] {} <Fatal> : Logical error: 'Part all_0_4_7_17 doesn't exist'.

```

https://clickhouse-test-reports.s3.yandex.net/0/9bb4d8769f1064ada4cce6b26d8ff61c11356965/stress_test_(debug).html#fail1
std::make_unique<BackupEntryFromImmutableFile>(disk, hardlink_filepath, checksum.file_size, file_hash, temp_dir_owner));
        }
        for (const auto & filepath : part->getFileNamesWithoutChecksums())
        {
            String relative_filepath = fs::path(part->relative_path) / filepath;
            backup_entries.emplace_back(relative_filepath, std::make_unique<BackupEntryFromSmallFile>(disk, part_dir / filepath));
        }
    }
    return backup_entries;
}
RestoreDataTasks MergeTreeData::restoreDataPartsFromBackup(const BackupPtr & backup, const String & data_path_in_backup,
                                                           const std::unordered_set<String> & partition_ids,
                                                           SimpleIncrement * increment)
{
    RestoreDataTasks restore_tasks;
    Strings part_names = backup->list(data_path_in_backup);
    for (const String & part_name : part_names)
    {
        MergeTreePartInfo part_info;
        if (!MergeTreePartInfo::tryParsePartName(part_name, &part_info, format_version))
            continue;
        if (!partition_ids.empty() && !partition_ids.contains(part_info.partition_id))
            continue;
        UInt64 total_size_of_part = 0;
        Strings filenames = backup->list(data_path_in_backup + part_name + "/", "");
        for (const String & filename : filenames)
            total_size_of_part += backup->getSize(data_path_in_backup + part_name + "/" + filename);
        std::shared_ptr<IReservation> reservation = getStoragePolicy()->reserveAndCheck(total_size_of_part);
        auto restore_task = [this,
                             backup,