Cache_redis, delete() method: Removing code for updating the internal cache, it is useless.
diff --git a/system/libraries/Cache/drivers/Cache_redis.php b/system/libraries/Cache/drivers/Cache_redis.php
index c0200aa..9fbdc65 100644
--- a/system/libraries/Cache/drivers/Cache_redis.php
+++ b/system/libraries/Cache/drivers/Cache_redis.php
@@ -139,13 +139,6 @@
 	 */
 	public function delete($key)
 	{
-		if (($index_key = array_search($key, $this->_serialized, TRUE)) !== FALSE)
-		{
-			unset($this->_serialized[$index_key]);
-		}
-
-		$this->_redis->sRemove(self::KEY_SET_FOR_SERIALIZATION, $key);
-
 		return ($this->_redis->delete($key) === 1);
 	}