---
fixes:
  - |
    Clarify the ``--block-device-mapping`` option of the ``server create``
    command: fix ValueError when the ``--block-device-mapping`` option's
    argument is in the wrong format; support creating a block device from
    a snapshot; add details to the help output about the option format.
    [Bug `1667266 <https://bugs.launchpad.net/python-openstackclient/+bug/1667266>`_]