Description:
------------
---
From manual page: http://www.php.net/datetime.add
---

If the sum has fraction of a second, the method fails if the result of the fraction is exactly one second. In other cases, it works well.

Test script:
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<?php
$objDataHora = date_create("2017-12-31T23:59:59.200");
$objIntervalo = new DateInterval("PT0S");
$objIntervalo->f = 0.700;
$objDataHora = date_add($objDataHora, $objIntervalo);
$strDataHora = date_format($objDataHora, "Y-m-d\TH:i:s.v");
echo("<p>$strDataHora</p>\n"); // 2017-12-31T23:59:59.900 - it's OK, the sum is correct
$objDataHora = date_create("2017-12-31T23:59:59.400");
$objIntervalo = new DateInterval("PT0S");
$objIntervalo->f = 0.700;
$objDataHora = date_add($objDataHora, $objIntervalo);
$strDataHora = date_format($objDataHora, "Y-m-d\TH:i:s.v");
echo("<p>$strDataHora</p>\n"); // 2018-01-01T00:00:00.100 - it's OK, the sum is correct
$objDataHora = date_create("2017-12-31T23:59:59.300");
$objIntervalo = new DateInterval("PT0S");
$objIntervalo->f = 0.700;
$objDataHora = date_add($objDataHora, $objIntervalo);
$strDataHora = date_format($objDataHora, "Y-m-d\TH:i:s.v");
echo("<p>$strDataHora</p>\n"); // 2017-12-31T23:59:59.1000 - it isn't OK, the sum is incorrect!
?>

Expected result:
----------------
In third echo: 2018-01-01T00:00:00.000

Actual result:
--------------
In third echo: 2017-12-31T23:59:59.1000