NFS update_migrated_volume should print a better message

[Eric Harney]

try:
    os.rename(current_path, original_path)
except OSError:
    LOG.error('Unable to rename the logical volume '
              'for volume: %s', volume.id)

This should log errno, so it's possible to find out more about the error here.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/653074
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=326d2bcb9b8dbffc003b07243649dfbce69b3c67
Submitter: Zuul
Branch: master

commit 326d2bcb9b8dbffc003b07243649dfbce69b3c67
Author: Eric Harney <email address hidden>
Date: Tue Apr 16 14:22:52 2019 -0400

    NFS: Log exception when update_migrated_volume fails

    There isn't enough log context here to debug
    some failures, ensure that the OSError exception
    information is logged to provide sufficient info.

    Closes-Bug: #1825029
    Change-Id: Ie499f7d914848b185531f101be49424fe8c64da6

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 15.0.0.0rc1 release candidate.