check the value of the configuration item num_vbd_unplug_retries

[zhangtralon]

we need to to check the value of the configuration item num_vbd_unplug_retries in the code in order to ensure the " num_vbd_unplug_retries " equal or bigger than 0 , done like that the configuration item network_allocate_retries

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/123321

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/123321
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=fd40541cafb2af643062dbdce87478aea3cc7bfc
Submitter: Jenkins
Branch: master

commit fd40541cafb2af643062dbdce87478aea3cc7bfc
Author: <email address hidden> <email address hidden>
Date: Tue Sep 23 11:32:40 2014 +0800

    check the configuration num_vbd_unplug_retries

    we need to to check the value of the configuration item
    num_vbd_unplug_retries in the code in order to ensure the "
    num_vbd_unplug_retries " equal or bigger than 0 , done like that the
    configuration item network_allocate_retries

    Change-Id: I076d35d2c4a54816b00345a6ef563853e2abae11
    Closes-Bug: #1372436