Update MemcacheEngine.php

removed 0 from getExtendedStats('slabs') in my last commit, someone point that out in the comment. Adding it back.

lib/Cake/Cache/Engine/MemcacheEngine.php

@@ -205,7 +205,7 @@ public function clear($check) {
 		if ($check) {
 			return true;
 		}
-		foreach ($this->_Memcache->getExtendedStats('slabs') as $slabs) {
+		foreach ($this->_Memcache->getExtendedStats('slabs', 0) as $slabs) {
 			foreach (array_keys($slabs) as $slabId) {
 				if (!is_numeric($slabId)) {
 					continue;