### ClickHouse release v20.6.7.4-stable FIXME as compared to v20.6.6.7-stable

#### Bug Fix
* Backported in [#14726](https://github.com/ClickHouse/ClickHouse/issues/14726): Cleanup data directory after Zookeeper exceptions during CreateQuery for StorageReplicatedMergeTree Engine. [#14563](https://github.com/ClickHouse/ClickHouse/pull/14563) ([Bharat Nallan](https://github.com/bharatnc)).
* Backported in [#14805](https://github.com/ClickHouse/ClickHouse/issues/14805): Fix bug when `ALTER UPDATE` mutation with Nullable column in assignment expression and constant value (like `UPDATE x = 42`) leads to incorrect value in column or segfault. Fixes [#13634](https://github.com/ClickHouse/ClickHouse/issues/13634), [#14045](https://github.com/ClickHouse/ClickHouse/issues/14045). [#14646](https://github.com/ClickHouse/ClickHouse/pull/14646) ([alesapin](https://github.com/alesapin)).
* Backported in [#14723](https://github.com/ClickHouse/ClickHouse/issues/14723): Fixed missed default database name in metadata of materialized view when executing `ALTER ... MODIFY QUERY`. [#14664](https://github.com/ClickHouse/ClickHouse/pull/14664) ([Alexander Tokmakov](https://github.com/tavplubix)).
* Backported in [#14913](https://github.com/ClickHouse/ClickHouse/issues/14913): Fix SIGSEGV for an attempt to INSERT into StorageFile(fd). [#14887](https://github.com/ClickHouse/ClickHouse/pull/14887) ([Azat Khuzhin](https://github.com/azat)).
* Backported in [#14945](https://github.com/ClickHouse/ClickHouse/issues/14945): Fix the issue when some invocations of `extractAllGroups` function may trigger "Memory limit exceeded" error. This fixes [#13383](https://github.com/ClickHouse/ClickHouse/issues/13383). [#14889](https://github.com/ClickHouse/ClickHouse/pull/14889) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
