Error while host confirmation (bootstrap.py)

[c6401@root:~]$ cat /var/run/ambari-server/bootstrap/1/bootstrap.err
INFO:root:BootStrapping hosts ['c6401.ambari.apache.org'] using /usr/lib/python2.6/site-packages/ambari_server cluster primary OS: redhat6 with user 'root' sshKey File /var/run/ambari-server/bootstrap/1/sshKey password File null using tmp dir /var/run/ambari-server/bootstrap/1 ambari: c6401.ambari.apache.org; server_port: 8080; ambari version: 1.5.0
INFO:root:Executing parallel bootstrap
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib64/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/site-packages/ambari_server/bootstrap.py", line 451, in run
    last_retcode = ret["exitstatus"]
TypeError: 'int' object is unsubscriptable

[c6401@root:~]$