There is no way to only check once for user password history

[wangxiyuan]

The config option "unique_last_password_count" can limit users password history. But the value is 2 at least. (1 means no limit). It means that the user need to change password at least twice. The case "pw1 -> pw2 -> pw1" is not covered.

We should make "unique_last_password_count"'s minimum to 0. Set to 1 means users can't change password like pw1 -> pw1, but can do "pw1 -> pw2 -> pw1".

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/593476

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/593476
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=34609d557e68020c6a054282c4d206aaa26a0d67
Submitter: Zuul
Branch: master

commit 34609d557e68020c6a054282c4d206aaa26a0d67
Author: wangxiyuan <email address hidden>
Date: Mon Aug 20 11:02:52 2018 +0800

    Change unique_last_password_count default to 0

    Changing the default value of unique_last_password_count from
    1 to 0, so that it can handle a case(when set to 1) that the
    password history check only check one previous password.

    Change-Id: Id368c99ca4926c995ea47959a6c3a438fffe1823
    Closes-Bug: #1787874

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/keystone 15.0.0.0rc1 release candidate.