Deploying remote DWH DB is failing with error "SSHException: could not get keys from ssh-agent"

Issue

• Executing an engine-setup to deploy a remote data warehouse failed with error SSHException: could not get keys from ssh-agent.

2018-08-01 10:39:58,263+0800 DEBUG otopi.plugins.ovirt_engine_common.base.remote_engine.remote_engine_root_ssh remote_engine_root_ssh._ssh_connect:172 exception
Traceback (most recent call last):
  File "/usr/share/ovirt-engine/setup/bin/../plugins/ovirt-engine-common/base/remote_engine/remote_engine_root_ssh.py", line 162, in _ssh_connect
    osetupcons.ConfigEnv.REMOTE_ENGINE_HOST_CLIENT_KEY
  File "/usr/lib/python2.7/site-packages/paramiko/client.py", line 380, in connect
    look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host)
  File "/usr/lib/python2.7/site-packages/paramiko/client.py", line 554, in _auth
    self._agent = Agent()
  File "/usr/lib/python2.7/site-packages/paramiko/agent.py", line 363, in __init__
    self._connect(conn)
  File "/usr/lib/python2.7/site-packages/paramiko/agent.py", line 68, in _connect
    raise SSHException('could not get keys from ssh-agent')
SSHException: could not get keys from ssh-agent