Description:
------------
---
From manual page: http://www.php.net/memcached.getbykey#refsect1-
memcached.getbykey-returnvalues
---

Memcached::getByKey returns false when cas requested.

Test script:
---------------
$mc = new Memcached('MEMCACHED_SERVER_ID');
$mc->addServer('localhost', 11211);

var_dump(
    $mc->setByKey('server', 'key', 'set_value'),
    $mc->getResultMessage(),
    $mc->getResultCode(),
    '-----------------------------------',
    $mc->getByKey('server', 'key', null, $cas),
    $mc->getResultMessage(),
    $mc->getResultCode(),
    $cas,
    '-----------------------------------',
    $mc->getByKey('server', 'key'),
    $mc->getResultMessage(),
    $mc->getResultCode()
);

Expected result:
----------------
bool(true)
string(7) "SUCCESS"
int(0)
string(35) "-----------------------------------"
string(9) "set_value"
string(7) "SUCCESS"
int(0)
float(17086)
string(35) "-----------------------------------"
string(9) "set_value"
string(7) "SUCCESS"
int(0)

Actual result:
--------------
bool(true)
string(7) "SUCCESS"
int(0)
string(35) "-----------------------------------"
bool(false)
string(7) "SUCCESS"
int(0)
float(17086)
string(35) "-----------------------------------"
string(9) "set_value"
string(7) "SUCCESS"
int(0)