Description:
------------
Memcached::setMulti can't support pure digit key

file: php_memcached.c
fun:  php_memc_setMulti_impl
line: 1009

if (zend_hash_get_current_key_ex(Z_ARRVAL_P(entries), &str_key, 
&str_key_len, &num_key, 0, NULL) != HASH_KEY_IS_STRING) {
			continue;
		}
HASH_KEY_IS_STRING is not good ideal.



Reproduce code:
---------------
---
From manual page: memcached.setmulti#Description
---
$m = new Memcached();
$m->addServer('localhost', 11211);

$items = array(
    '123' => 'value1'            // key is pure number but that type is string, and php engine will turn string(123) to int(123) key.
);
$m->setMulti($items);
var_dump($m->get('123'));         // '123'=>'value1' not in memcached 


Expected result:
----------------
string(6) "value1"

Actual result:
--------------
bool(false)