Description:
------------
When the result of a statement isn't freed PHP gives an error when trying to issue a new query. It doesn't so when the new query is preparing a statement (see reproduce code). Then mysqli::errno and mysqli::error are empty.

workaround:
use $stmt to decide wheter $stmt = $mysqli->prepare(...) worked not $mysqli->errno.

Reproduce code:
---------------
<?php
$my = new mysqli("localhost","user","password","db");
$stmta = $my->prepare("SELECT * FROM cms_Site");
$stmta->execute();
$stmtb = $my->prepare("SELECT * FROM cms_Site");
if ($stmtb) {
	echo "prepare succeeded";
} else {
	echo "prepare failed<br />";
	echo "errno: ", $my->errno, "  - error: ", $my->error, "<br />";
}
$x = $my->query("") or die("errno: ".$my->errno."  - error: ".$my->error."<br />");
?>

Expected result:
----------------
prepare failed
errno: 2014 - error: Commands out of sync; you can't run this command now
errno: 2014 - error: Commands out of sync; you can't run this command now

Actual result:
--------------
prepare failed
errno: 0 - error:
errno: 2014 - error: Commands out of sync; you can't run this command now