In core/db_mysql41.php:
function db_connect($db_host, $db_user, $db_password, $clean = false)
{
$db_conn = mysqli_connect($db_host, $db_user, $db_password);
if ($db_conn) {
mysqli_set_charset($db_conn, 'utf8');
mysqli_query($db_conn, "SET collation_connection = 'utf8_general_ci'");
}
return $db_conn;
}