Description:
------------
Using a variable to instantiate a namespaced class (eg, new $foo();) causes truncated data to be passed to the autoloader when the class is prepended with \.

Reproduce code:
---------------
<?php
// File 1
$baz = '\\Foo\\Bar\\Baz';
new $baz();
function __autoload($class) {
    var_dump($class);
    require './test.php';
}
?>
<?php
// File 2
namespace Foo\Bar;
class Baz {
}
?>

Expected result:
----------------
Foo\Bar\Baz or \Foo\Bar\Baz in the var_dump

Actual result:
--------------
\Foo\Bar\Ba (missing the z)