Description:
------------
Hi,

on the manual page for Phar::mount some information is missing that may confuse users when using this method.

1. Unlike unix mount it is not possible to mount an external location to an existing path inside the phar. $pharpath must not exist or mount will fail.

2. When calling from inside a phar it not only may be a relative path, it MUST be a relative path or mount will fail. Mounting to foreign pahr locations inside a phar is not possible.

---
From manual page: http://www.php.net/phar.mount%23Description
---


Test script:
---------------
<?php

$phar = new Phar('file.phar');
$phar->startBuffering();
$phar->addStub('<?php require_once "phar://file.phar/index.php"; __HALT_COMPILER();');
$phar->addEmptyDir('foo');
$phar->addFromString('index.php', '<?php
// This will Fail!
Phar::mount("foo", "/etc/foo");

// This Will also fail:
Phar::mount('phar:///home/www/some.other.phar/bar', '/tmp/info');
');
$phar->stopBuffering();

Expected result:
----------------
As documented I expected both mounts to work, but they don't

Actual result:
--------------
Code is throwing PharException