display of subnet information broken if service_types attribute not present

[Per Boussard]

With at least versions 3.5 and 3.6 of python openstack-client (maybe even previous versions, I have not made an exhaustive investigation) there seems to be an assumption that a query for subnet information will return a service_types element in the JSON data returned for e.g. "openstack subnet show '<subnet name>'". If the returned JSON data does not contain such an element, the method utils.format_list of the lib-osc will receive a None argument, which causes python-openstackclient to throw an exception since None is not an enumerable type.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/434768

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/434768
Committed: https://git.openstack.org/cgit/openstack/osc-lib/commit/?id=e45dc8776e7c44ffb09f650b12b65246e5d2b375
Submitter: Jenkins
Branch: master

commit e45dc8776e7c44ffb09f650b12b65246e5d2b375
Author: Huanxuan Ao <email address hidden>
Date: Thu Feb 16 17:15:44 2017 +0800

    Avoid 'NoneType' error when format conversion

    Error raise when changing a 'None' data to a new format:
    "TypeError: 'NoneType' object is not iterable"
    we also met that bug before in the previous patch [1]

    This change is to handle the 'None' data and avoid
    the error

    [1] https://review.openstack.org/#/c/420420/

    Change-Id: I649b4fc65ef7c19b8193b07f3bd59f00e6095f9f
    Closes-bug: #1656363

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/osc-lib 1.4.0 release.