xtrabackup_56 2.1.4 ro4 MySQL server 5.6.11 dont recognisies flush_method = ALL_O_DIRECT

Bug appeared again in
xtrabackup_56 version 2.1.4 for MySQL server 5.6.11 Linux (x86_64) (revision id: 656)

[<email address hidden> /home/banyek]# innobackupex /tmp/test/

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona Ireland Ltd 2009-2012. All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

131217 14:41:42 innobackupex: Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup' (using password: NO).
131217 14:41:42 innobackupex: Connected to MySQL server
IMPORTANT: Please check that the backup run completes successfully.
           At the end of a successful backup run innobackupex
           prints "completed OK!".

innobackupex: Using mysql server version 5.6.14-56-log

innobackupex: Created backup directory /tmp/test/2013-12-17_14-41-42

131217 14:41:42 innobackupex: Starting ibbackup with command: xtrabackup_56 --defaults-group="mysqld" --backup --suspend-at-end --target-dir=/tmp/test/2013-12-17_14-41-42 --tmpdir=/tmp
innobackupex: Waiting for ibbackup (pid=25593) to suspend
innobackupex: Suspend file '/tmp/test/2013-12-17_14-41-42/xtrabackup_suspended_2'

xtrabackup_56 version 2.1.4 for MySQL server 5.6.11 Linux (x86_64) (revision id: 656)
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /var/lib/mysql
xtrabackup: using the following InnoDB configuration:
xtrabackup: innodb_data_home_dir = ./
xtrabackup: innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 2147483648
xtrabackup: Unrecognized value ALL_O_DIRECT for innodb_flush_method
innobackupex: Error: ibbackup child process has died at /usr/bin/innobackupex line 416.

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Right after commented out the
innodb_flush_method = ALL_O_DIRECT
from /etc/my.cnf it started working. <- but we can agree this is not the best workaround? ;)