Specifying API version in clouds.yaml doesn't always work

[David Comay]

I suspect this is user error but filing this since it seems to be a bug.

All all of our nodes support a Compute API of 2.90, I was hoping we could use `clouds.yaml` to indicate that to avoid needing to pass `--os-compute-api-version` on the command line.

However, using a `clouds.yaml` file of the form

clouds:
  mycloud:
    auth:
      .
      .
    compute_api_version: 2.90

doesn't seem to work in that if I try the command

    openstack --os-cloud mycloud server migrate --live-migration --host newhost --wait <uuid>

I get the error

    --os-compute-api-version 2.30 or greater is required when using --host

The code in question from MigrateServer's take_action() method,

            if (
                parsed_args.host and
                compute_client.api_version < api_versions.APIVersion('2.30')
            ):
                raise exceptions.CommandError(
                    '--os-compute-api-version 2.30 or greater is required '
                    'when using --host'
                )

If I actually specify this via the CLI, --os-compute-api-version 2.90, the command succeeds.