Removing _expires keys made with Memcache cache engine. These did not…

… add any value as Memcache already handles expiration of keys. Fixes #871

cake/libs/cache/memcache.php

@@ -105,7 +105,6 @@ function init($settings = array()) {
  */
 	function write($key, &$value, $duration) {
 		$expires = time() + $duration;
-		$this->__Memcache->set($key . '_expires', $expires, $this->settings['compress'], $expires);
 		return $this->__Memcache->set($key, $value, $this->settings['compress'], $expires);
 	}
 
@@ -117,11 +116,6 @@ function write($key, &$value, $duration) {
  * @access public
  */
 	function read($key) {
-		$time = time();
-		$cachetime = intval($this->__Memcache->get($key . '_expires'));
-		if ($cachetime < $time || ($time + $this->settings['duration']) < $cachetime) {
-			return false;
-		}
 		return $this->__Memcache->get($key);
 	}