Description:
------------
lastInsertId always return 0 after call exec("INSERT ...")


Reproduce code:
---------------
When using

$dbh->exec("INSERT INTO ... ");
$dbh->lastInsertId();   //return always 0
// + good Error Info for any error (268, 691, ...)

when using

$stmt = $dbh->prepare("INSERT INTO ... ");
$stmt->execute();
$dbh->lastInsertId();   //this work OK  
// + bad Error Info for error , how reported in bug#13115