**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
{
    const auto settings = getSettings();
    const size_t parts_count_in_total = getPartsCount();
    if (parts_count_in_total >= settings->max_parts_in_total)
    {
        ProfileEvents::increment(ProfileEvents::RejectedInserts);
        throw Exception("Too many parts (" + toString(parts_count_in_total) + ") in all partitions in total. This indicates wrong choice of partition key. The threshold can be modified with 'max_parts_in_total' setting in <merge_tree> element in config.xml or with per-table setting.", ErrorCodes::TOO_MANY_PARTS);
    }
    size_t parts_count_in_partition = getMaxPartsCountForPartition();
    ssize_t k_inactive = -1;
    if (settings->inactive_parts_to_throw_insert > 0 || settings->inactive_parts_to_delay_insert > 0)
    {
        size_t inactive_parts_count_in_partition = getMaxInactivePartsCountForPartition();
        if (settings->inactive_parts_to_throw_insert > 0 && inactive_parts_count_in_partition >= settings->inactive_parts_to_throw_insert)
        {
            ProfileEvents::increment(ProfileEvents::RejectedInserts);
            throw Exception(
                ErrorCodes::TOO_MANY_PARTS,
                "Too many inactive parts ({}). Parts cleaning are processing significantly slower than inserts",
                inactive_parts_count_in_partition);
        }
        k_inactive = ssize_t(inactive_parts_count_in_partition) - ssize_t(settings->inactive_parts_to_delay_insert);
    }
    if (parts_count_in_partition >= settings->parts_to_throw_insert)
    {
        ProfileEvents::increment(ProfileEvents::RejectedInserts);
        throw Exception(