Listing grants in v3 can issue an un-caught exception

[Henry Nash]

The current metadata code in keystone/identity/backends/sql.py will issue an exception if there is no metadata (i.e. role assignments) for a particular entity pair (e.g. User-Project). This is meant to be caught by callers - but this is not always the case (e.g. list grants).

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/18097
Committed: http://github.com/openstack/keystone/commit/4fae928c59beaa558306a5aa3a3aa5c6f4945b70
Submitter: Jenkins
Branch: master

commit 4fae928c59beaa558306a5aa3a3aa5c6f4945b70
Author: Henry Nash <email address hidden>
Date: Thu Dec 13 16:48:13 2012 +0000

    Keystone server support for user groups

    This implements the server side of groups of users. This
    set of code provides all the crud functionality for groups as
    well as the corresponding support for role assignments.

    blueprint user-groups

    The following deficiencies existing with the current version and
    will be corrected ahead of the final Grizzly release:

    1) There is only placeholder support for LDAP (Bug #1092187)
    2) Domain role grants are accepted but not yet honored (Bug #1093248)
    3) Token invalidation does not occur with group changes (Bug #1093493)

    This update also fills in missing v3 grant unit testing and v3 grant
    support within the kvs backend. In addition, there is a fix for
    Bug #1092200 (uncaught exception when listing grants)

    DocImpact

    Change-Id: Ibd1783b04b2d7804eff90312e5ef591dca4d0695