Hive generates a add partition event with empty partition list

If the user issues a alter table <table> add if not exists partition <partition_spec> and it the partition already exists, no partition is added. However, metastore still generates a ADD_PARTITION event with empty partition list. An alter table <table> drop if exists partition <partition_spec> does not generate the DROP_PARTITION event in case the partition is not existing.

This behavior is inconsistent and misleading. Metastore should not generate such add_partition events.