'Fixed IP xxx.xxx.xxx.xxx is already in use' error occurs in test_create_list_show_delete_interfaces

[zhufl]

Problem:
    running test_create_list_show_delete_interfaces failes with error message "Fixed IP 172.168.200.1 is already in use."

Details:
    400 POST http://10.43.211.20:8774/v2/df674fd4cd054aa692ea53f7f6182a33/servers/5e00abec-cdd6-4acf- a0f9-afccc812495f/os-interface 0.774s

    2016-08-25 10:47:22.376 24558 DEBUG tempest.lib.common.rest_client [req-dc231c86-5d88-4f7f- 9495-d46c16e50d1e ]
    Request-Head: {}
                  Request-Body: {"interfaceAttachment": {"fixed_ips": [{"ip_address": "172.168.200.1"}], "net_id": "d36cf451-5a20-41e1-b04d-0d65e44e75d2"}}

    Response-Head: {'status': '400', 'content-length': '85'}
                  Response-Body: {"badRequest": {"message": "Fixed IP 172.168.200.1 is already in use.", "code": 400}}

Reason:
    There is gateway_ip in subnet used by the testcase

    [root@host-10-43-211-174]# neutron subnet-show 29a62fa8-68ed-42fe-83db-9996fcf37a6d
    +-------------------+------------------------------------------------------+
    | Field | Value |
    +-------------------+------------------------------------------------------+
    | allocation_pools | {"start": "172.168.200.2", "end": "172.168.200.254"} |
    | cidr | 172.168.200.0/24 |
    | dns_nameservers | |
    | enable_dhcp | True |
    | gateway_ip | 172.168.200.1 |
    | host_routes | |
    | id | 29a62fa8-68ed-42fe-83db-9996fcf37a6d |
    | ip_version | 4 |
    | ipv6_address_mode | |
    | ipv6_ra_mode | |
    | name | subnet01 |
    | network_id | d36cf451-5a20-41e1-b04d-0d65e44e75d2 |
    | subnetpool_id | |
    | tenant_id | 1f758ff53e0e472687e39e09621ec13c |
    +-------------------+------------------------------------------------------+

Solution:
    In get_unused_ip_addresses, gateway_ip of the subnet should be excluded

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/360199

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/360199
Committed: https://git.openstack.org/cgit/openstack/tempest/commit/?id=8458ddec1cb187a53fe3031bb6059058bed96bbd
Submitter: Jenkins
Branch: master

commit 8458ddec1cb187a53fe3031bb6059058bed96bbd
Author: zhufl <email address hidden>
Date: Thu Aug 25 11:29:13 2016 +0800

    Exclude gateway_ip of subnet in get_unused_ip_addresses

    When running test_create_list_show_delete_interfaces, if subnet
    used by the testcase has gateway_ip set, a BadRequest exception
    will occur with error message something like "Fixed IP 172.168.200.1
    is already in use."
    This is to exclude gateway_ip of subnet in get_unused_ip_addresses
    besides pruning out addresses already allocated to existing ports.

    Change-Id: I036d2940ff39450ca30d19be1cd9ae581ffb1b4f
    Closes-Bug: 1616714