Neutron validation doesn't allow '0' as max _l3_agents_per_router

[Yoni Shafrir]

The 'neutron.conf' states in it's comments the following:

# Maximum number of l3 agents which a HA router will be scheduled on. If it
# is set to 0 the router will be scheduled on every agent.
# max_l3_agents_per_router = 3

In practice this is not allowed in '_verify_configuration' in 'L3_HA_NAT_db_mixin'.
a 'HAMaximumAgentsNumberNotValid' exception is raised.

This is due to this change it seems :

https://review.openstack.org/#/c/140340/11

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/149947

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/149947
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=421b5cd43b52e1fcec0713a9ad29bf9c90b5f45b
Submitter: Jenkins
Branch: master

commit 421b5cd43b52e1fcec0713a9ad29bf9c90b5f45b
Author: Yoni Shafrir <email address hidden>
Date: Mon Jan 26 09:32:55 2015 +0200

    Allow 'max_l3_agents_per_router' to be set to '0'

    Currently the field 'max_l3_agents_per_router' from
    'neutron.conf' cannot be set to '0' even though the comments
    and code indicate it is be supported. The value
    means 'unlimited' agents per router is allowed on HA routers.

    This issue is a regression that was caused by:
    7da314434e445ce3a6f3642c784954ef61154b7f

    This patch adds a special handling for this value when validating
    the config. When a value of '0' is used, the further validation
    of max value is skipped.

    Change-Id: Iac85768b350ee16c34893218738974a2692202aa
    Closes-Bug: #1414548