Improve ext/session error messages
diff --git a/system/libraries/Session/drivers/Session_redis_driver.php b/system/libraries/Session/drivers/Session_redis_driver.php
index 7b7951f..cc242dd 100644
--- a/system/libraries/Session/drivers/Session_redis_driver.php
+++ b/system/libraries/Session/drivers/Session_redis_driver.php
@@ -131,7 +131,7 @@
 	{
 		if (empty($this->_config['save_path']))
 		{
-			return $this->_failure;
+			return $this->_fail();
 		}
 
 		$redis = new Redis();
@@ -153,7 +153,7 @@
 			return $this->_success;
 		}
 
-		return $this->_failure;
+		return $this->_fail();
 	}
 
 	// ------------------------------------------------------------------------
@@ -183,7 +183,7 @@
 			return $session_data;
 		}
 
-		return $this->_failure;
+		return $this->_fail();
 	}
 
 	// ------------------------------------------------------------------------
@@ -201,14 +201,14 @@
 	{
 		if ( ! isset($this->_redis))
 		{
-			return $this->_failure;
+			return $this->_fail();
 		}
 		// Was the ID regenerated?
 		elseif ($session_id !== $this->_session_id)
 		{
 			if ( ! $this->_release_lock() OR ! $this->_get_lock($session_id))
 			{
-				return $this->_failure;
+				return $this->_fail();
 			}
 
 			$this->_key_exists = FALSE;
@@ -227,15 +227,15 @@
 					return $this->_success;
 				}
 
-				return $this->_failure;
+				return $this->_fail();
 			}
 
 			return ($this->_redis->setTimeout($this->_key_prefix.$session_id, $this->_config['expiration']))
 				? $this->_success
-				: $this->_failure;
+				: $this->_fail();
 		}
 
-		return $this->_failure;
+		return $this->_fail();
 	}
 
 	// ------------------------------------------------------------------------
@@ -255,9 +255,9 @@
 				if ($this->_redis->ping() === '+PONG')
 				{
 					$this->_release_lock();
-					if ($this->_redis->close() === $this->_failure)
+					if ($this->_redis->close() === $this->_fail())
 					{
-						return $this->_failure;
+						return $this->_fail();
 					}
 				}
 			}
@@ -296,7 +296,7 @@
 			return $this->_success;
 		}
 
-		return $this->_failure;
+		return $this->_fail();
 	}
 
 	// ------------------------------------------------------------------------