Comment 2 for bug 1679934

Reviewed: https://review.openstack.org/453490
Committed: https://git.openstack.org/cgit/openstack/python-ceilometerclient/commit/?id=499be2f7586698d50ba0e9a82433c535f8017523
Submitter: Jenkins
Branch: master

commit 499be2f7586698d50ba0e9a82433c535f8017523
Author: zhangjianfeng <kill51216@163.com>
Date: Wed Apr 5 15:00:54 2017 +0800

    [bugfix]with keystone v3 Could not find domain: default.

    when we use adminrc with keystone v3 not set OS_PROJECT_DOMAIN_ID
    OS_USER_DOAMIN_ID,default ceilometerclient code will set it to
    string default.this will lead error.

    value is often like fdc79c4b63e8492d98271412320e8672
    so when change this code to set it as None.
    last we delete the user_domain_id and project_domain_id
    because it is not useful.

    closes-bug: 1679934

    Change-Id: I95c994406ed7a0b15ba6446e80f01e4f6787ec20