“FOR system_time ALL”是否应该包括开始时间和结束时间相等的行？

使用 查询系统版本控制的时态表FOR system_time ALL似乎会忽略开始时间和结束时间相等的行。

例如：

/* Create a simple system-versioned table */
CREATE TABLE [dbo].[svt_test](
    [string] [VARCHAR](30) NOT NULL,
    [validFrom] [DATETIME2](7) GENERATED ALWAYS AS ROW START NOT NULL,
    [validTo]   [DATETIME2](7) GENERATED ALWAYS AS ROW END NOT NULL,
CONSTRAINT [PK_svt_test] PRIMARY KEY CLUSTERED 
(
    [string] ASC
),
    PERIOD FOR SYSTEM_TIME ([validFrom], [validTo])
) 
WITH
(
    SYSTEM_VERSIONING = ON ( HISTORY_TABLE = [dbo].[svt_test_history] )
);

/* 
Insert and immediately delete a row. 
May have to try multiple times to get a row with the same start and end    
timestamp. 
*/
INSERT INTO dbo.svt_test (string) VALUES ('string'); 
DELETE dbo.svt_test WHERE string = 'string';

/* 0 rows */
SELECT * FROM dbo.svt_test;
/* 1 row */
SELECT * FROM dbo.svt_test_history;
/* 
0 rows. 
Should be the "union of rows that belong to the current and the history table" 
  per https://msdn.microsoft.com/en-us/library/dn935015.aspx 
*/
SELECT * FROM dbo.svt_test FOR system_time ALL;

/* 
   CONTAINED IN does not find the row either, even though MSDN says the    
   interval is defined as SysStartTime >= start_date_time AND SysEndTime <=   
   end_date_time
*/
DECLARE @Start DATETIME2(7);
SELECT @Start = validFrom FROM [dbo].[svt_test_history] WHERE string = 'string';
DECLARE @End DATETIME2(7);
SELECT @End = validTo FROM [dbo].[svt_test_history] WHERE string = 'string';
SELECT * FROM dbo.svt_test FOR system_time CONTAINED IN (@Start, @End);

/* Clean up */
ALTER TABLE dbo.svt_test SET (SYSTEM_VERSIONING = OFF);
DROP TABLE dbo.svt_test;
DROP TABLE dbo.svt_test_history;

我已经在 2016 SP1 CU1 (12.0.4416) 和 2016 CU3 (13.0.2186) 上对此进行了验证。我用datetime2(0)而不是得到了相同的结果datetime2(7)。

有人会碰巧知道这可能是错误还是设计使然？或者，也许我误解了什么？