Description:
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PDO::exec under postgresql driver returns 1 even when there are no rows affected

Reproduce code:
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Tehre are no rows in table with index==20
<?php

$db_connection = new PDO("pgsql:host=localhost port=5432 dbname=test", "test", "test", array(PDO::ATTR_PERSISTENT => true));

print var_dump($db_connection->exec("DELETE FROM test WHERE index=20"));

?>

Expected result:
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int(0)


Actual result:
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int(1)