Description of problem:
packstack install fails if ntp server does not respond

Version-Release number of selected component (if applicable):
openstack-packstack.noarch                                         2013.1.1-0.5.dev538.el6                                     @openstack-grizzly


How reproducible:
Happens about 5-10% of the time I try and run packstack install

Steps to Reproduce:
1.Run:
  packstack -answer-file=<file>

  
Actual results:
If one of the listed ntp server fails to respond the packstack install fails with:
Installing:
Clean Up...                                              [ DONE ]
Adding pre install manifest entries...                   [ DONE ]
Installing time synchronization via NTP...
ERROR : Given host is unreachable: 0.fedora.pool.ntp.org
Please check log file /var/tmp/packstack/20130425-203129-rs39W8/openstack-setup.log for more information

Expected results:
packstack should install

Additional info:
/var/tmp/packstack/20130425-203129-rs39W8/openstack-setup.log
2013-04-25 20:31:29::INFO::run_setup::366::root:: Comparing pre- conditions, value: 'False', and match: 'True'
2013-04-25 20:31:29::INFO::run_setup::366::root:: Comparing pre- conditions, value: 'False', and match: 'True'
2013-04-25 20:31:29::INFO::run_setup::366::root:: Comparing pre- conditions, value: 'y', and match: 'y'
2013-04-25 20:31:29::INFO::run_setup::366::root:: Comparing pre- conditions, value: 'yes', and match: 'yes'
2013-04-25 20:31:29::INFO::run_setup::366::root:: Comparing pre- conditions, value: 'yes', and match: 'yes'
2013-04-25 20:31:39::ERROR::run_setup::906::root:: Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/packstack/installer/run_setup.py", line 900, in main
    _main(confFile)
  File "/usr/lib/python2.6/site-packages/packstack/installer/run_setup.py", line 597, in _main
    runSequences()
  File "/usr/lib/python2.6/site-packages/packstack/installer/run_setup.py", line 574, in runSequences
    controller.runAllSequences()
  File "/usr/lib/python2.6/site-packages/packstack/installer/setup_controller.py", line 77, in runAllSequences
    sequence.run()
  File "/usr/lib/python2.6/site-packages/packstack/installer/setup_sequences.py", line 153, in run
    step.run()
  File "/usr/lib/python2.6/site-packages/packstack/installer/setup_sequences.py", line 60, in run
    function()
  File "/usr/lib/python2.6/site-packages/packstack/plugins/prescript_000.py", line 159, in create_ntp_manifest
    validators.validate_ping(srv)
  File "/usr/lib/python2.6/site-packages/packstack/installer/validators.py", line 184, in validate_ping
    raise ParamValidationError(msg % param)
ParamValidationError: Given host is unreachable: 0.fedora.pool.ntp.org