I could not believe it is. But that's true.

In function we have these lines:

	for (table = hk_cleanup_tables; NULL != table->name; table++)
	{
		if (ZBX_HK_MODE_REGULAR != *table->poption_mode || ZBX_HK_OPTION_ENABLED == *table->poption_global)
			continue;

Imagine that for some reason I decided to keep less history and/or trends than set per-item level.
I've just enabled "Override item history/trend period" checkbox(s) and set custom number of days.
I keep "Enable internal housekeeping" enabled for history/trends, as it was.

In a result, number of records in "housekeeper" table started to grow.
Zabbix server executes this SQL to select records for cleanup:

select housekeeperid,tablename,field,value from housekeeper where tablename in ('events') order by tablename

Why is this so?
How history/trends of deleted items is different from history/trends of existing items?
Why for deleted ones it's preserved but for existing ones it's cleaned up ?

I'm pretty sure this is regression.
If it's by design - it's absolutely not clear for user why such logic is used.

As I see this logic has been changed in version 4.2.
4.0 was fine in this regard.