automatic confirm resize should not set migration to error when encounter problem

[jichenjc]

function in compute/manager.py _poll_unconfirmed_resizes will translate the migrate status from finished to error
whenever it find a problem , consider following case

1) _poll_unconfirmed_resizes running, it found several migrations to be confirmed
2) user want to delete an instance ,its task state will be changed to DELETING by
3) _poll_unconfirmed_resized will found the task state is not None, it will make the migration error status
4) following code in _delete
if instance.vm_state == vm_states.RESIZED:
                self._confirm_resize_on_deleting(context, instance)
will fail because migration status already updated

so we should not set the migration status to 'error' , let it be and report warning message is enough

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/84932

[Openstack Gerrit (openstack-gerrit)]

Fix proposed to branch: master
Review: https://review.openstack.org/90634

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/90634
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0b2cf281be48e76a80e2fc73f00529f22e8d9126
Submitter: Jenkins
Branch: master

commit 0b2cf281be48e76a80e2fc73f00529f22e8d9126
Author: jichenjc <email address hidden>
Date: Mon Apr 28 11:42:04 2014 +0800

    Keep Migration status in automatic confirm-resize

    function in compute/manager.py _poll_unconfirmed_resizes
    will translate the migrate status from finished to error
    whenever finds a problem ,Consider the following case

    1) _poll_unconfirmed_resizes runs and founds several migrations to be confirmed
    2) user deletes the instance, so its task state will be changed to DELETING
    3) _poll_unconfirmed_resizes will find the task state is not None,
    it will make the migration error status
    4) following code in _delete
    if instance.vm_state == vm_states.RESIZED:
    self._confirm_resize_on_deleting(context, instance)
    will fail because migration status already updated

    User is able to do the migration operations when they found error
    so we don't need to handle this kind of error for them

    Change-Id: Ia79dd56c9c1fa8add7dc138d838cbfbac4523ac3
    Closes-Bug: #1301696