我正在安装 devstack Juno，最后它出现了一个错误，指出
撒哈拉无法启动
这是有关此错误的详细信息，我无法弄清楚，请帮助我。
/usr/local/bin/sahara-all --config-file /etc/sahara/sahara.conf
2015-02-15 20:53:21.426 INFO sahara.main [-] Starting Sahara all-in-one
2015-02-15 20:53:21.426 INFO sahara.utils.rpc [-] Notifications enabled
2015-02-15 20:53:22.676 INFO sahara.plugins.base [-] Plugin 'hdp' loaded sahara.plugins.hdp.ambariplugin:AmbariPlugin
2015-02-15 20:53:22.677 INFO sahara.plugins.base [-] Plugin 'vanilla' loaded sahara.plugins.vanilla.plugin:VanillaProvider
2015-02-15 20:53:22.677 INFO sahara.plugins.base [-] Plugin 'fake' loaded sahara.plugins.fake.plugin:FakePluginProvider
2015-02-15 20:53:22.725 DEBUG sahara.main [-] Logging of request/response exchange could be enabled using flag --log-exchange from (pid=847) make_app /opt/stack/sahara/sahara/main.py:144
2015-02-15 20:53:22.726 INFO keystonemiddleware.auth_token [-] Starting keystone auth_token middleware
2015-02-15 20:53:22.727 INFO keystonemiddleware.auth_token [-] Using /var/cache/sahara as cache directory for signing certificate
2015-02-15 20:53:22.819 WARNING keystonemiddleware.auth_token [-] signing_dir mode is 0755 instead of 0700
2015-02-15 20:53:22.820 CRITICAL sahara [-] TypeError: unsupported type for timedelta seconds component: str
2015-02-15 20:53:22.820 TRACE sahara Traceback (most recent call last):
2015-02-15 20:53:22.820 TRACE sahara File "/usr/local/bin/sahara-all", line 9, in <module>
2015-02-15 20:53:22.820 TRACE sahara load_entry_point('sahara==2014.2.3.dev1', 'console_scripts', 'sahara-all')()
2015-02-15 20:53:22.820 TRACE sahara File "/opt/stack/sahara/sahara/cli/sahara_all.py", line 56, in main
2015-02-15 20:53:22.820 TRACE sahara app = server.make_app()
2015-02-15 20:53:22.820 TRACE sahara File "/opt/stack/sahara/sahara/main.py", line 151, in make_app
2015-02-15 20:53:22.820 TRACE sahara app.wsgi_app = acl.wrap(app.wsgi_app, CONF)
2015-02-15 20:53:22.820 TRACE sahara File "/opt/stack/sahara/sahara/api/acl.py", line 31, in wrap
2015-02-15 20:53:22.820 TRACE sahara return auth_token.AuthProtocol(app, conf=auth_cfg)
2015-02-15 20:53:22.820 TRACE sahara File "/usr/local/lib/python2.7/dist-packages/keystonemiddleware/auth_token.py", line 661, in __init__
2015-02-15 20:53:22.820 TRACE sahara seconds=self._conf_get('revocation_cache_time'))
2015-02-15 20:53:22.820 TRACE sahara TypeError: unsupported type for timedelta seconds component: str
2015-02-15 20:53:22.820 TRACE sahara
sahara failed to start