Plug/unplug exceptions are a mess

[Eric Fried]

Need some consistency in the VirtualInterface(Un)Plug exceptions in the vif driver.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/newton
Review: https://review.openstack.org/380762

[Eric Fried (efried)]

https://review.openstack.org/#/c/380762/

[OpenStack Infra (hudson-openstack)]

Change abandoned by Eric Fried (<email address hidden>) on branch: stable/newton
Review: https://review.openstack.org/380762
Reason: In favor of proper cherry-pick: https://review.openstack.org/381836

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/381836
Committed: https://git.openstack.org/cgit/openstack/nova-powervm/commit/?id=e22a3e823e22657cc725d87a9464c4c41a9c396e
Submitter: Jenkins
Branch: stable/newton

commit e22a3e823e22657cc725d87a9464c4c41a9c396e
Author: Eric Fried <email address hidden>
Date: Fri Sep 2 08:35:20 2016 -0500

    HttpError=>VirtualInterface(Unp|P)lugException

    With this change set, the top-level vif driver plug/unplug methods trap
    HttpError (typically a 400 or 500) and convert it to the standard
    VirtualInterfacePlugException/VirtualInterfaceUnplugException from
    nova.exception.

    This change set also gets rid of the VirtualInterfaceUnplugException in
    vif.py and tasks/network.py, replacing their invocations with the
    corresponding nova.exception class.

    Conflicts:
     nova_powervm/tests/virt/powervm/test_vif.py

    Change-Id: Iad1197218cb8d8a260c00d55c9addd39ac3a6226
    Closes-Bug: #1629556