docker nova_libvirt can't start without libvirt.log

[YU CHENGDE]

Brief Description
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  If you delete the libvirtd.log in /var/lib/docker/volumes/kolla_logs/_data/libvirt docker
  nova_libvirt won't able to boot up after restarting.

Steps to Reproduce
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  1. delete the "libvirtd.log" in /var/lib/docker/volumes/kolla_logs/_data/libvirt.
  2. docker stop nova_compute.
  3. docker restart nova_libvirt.
  4. The issue happens.

Reference
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  Please refer docker log as attached file.

Expected Behavior
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  No matter the log existed or not, nova_libvirt should be able to restart normally.

Environment
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  Broswer: Chrome 77.0.3865.120
  OS: macOS Mojave 10.14.6
  kolla-ansible version: stable/master
  Openstack version: master
  Openstack deployed system: Centos Linux version 3.10.0-1062.1.2.el7.x86_64

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/697605

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/697605
Committed: https://git.openstack.org/cgit/openstack/kolla/commit/?id=6c2a2f536e071cf7dde74ae9b914a9c2f6323435
Submitter: Zuul
Branch: master

commit 6c2a2f536e071cf7dde74ae9b914a9c2f6323435
Author: yuchengde <[e-mail]>
Date: Fri Dec 6 00:30:20 2019 +0800

    Let nova-libvirt restarting be independent of libvirtd.log

    Modify nova-libvirt extend_start.sh for preventing docker boot fail if there is no libvirtd.log file in libvirt folder.

    Change-Id: If1df41fb07b90b6020a60e3f987d51f5a9792bca
    Closes-Bug: 1855253