Comment 3 for bug 1598661

Reviewed: https://review.openstack.org/337056
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=033d4d268960b18af806fdbe1bb2c1122d09782f
Submitter: Jenkins
Branch: master

commit 033d4d268960b18af806fdbe1bb2c1122d09782f
Author: Hiroyuki Eguchi <email address hidden>
Date: Mon Jul 4 08:14:25 2016 +0000

    libvirt: Delete duplicate check when live-migrating

    A year ago a useless check was added: I7989128d

    The above patch was aimed to enable live-migration when
    instance is booted from volume and has not local disk
    by adding a new check.

    However, the same check has been already checked in
    _is_shared_block_storage method.

    The last part of the _is_shared_block_storage method does
    the same that above patch does:
    - check whether the instance is booted from volume
    - check whether the instance has not a local disk

    Also this check calls _is_booted_from_volume incorrectly.
    Parameter disk_mapping of _is_booted_from_volume must be a dict, but
    this check specifies a string instead.

    And finally introduced _has_local_disk method is wrong, because
    it does not take into accont disk.ephN names.

    This change reverts I7989128d, improves and simplifies related tests.

    Closes-Bug: 1598661
    Related-Bug: 1469006
    Co-Authored-By: Feodor Tersin <email address hidden>
    Change-Id: Id59012547c3318d94b65ab9f7c37c33c3a08b0e0