Disabled neutron quota breaks "Create subnet" button

[Paul Karikh]

If we set OPENSTACK_NEUTRON_NETWORK= {'enable_quotas': False}, "Create subnet" button dissapears and we get the following error:

Error while checking action permissions.
Traceback (most recent call last):
  File "horizon/horizon/tables/base.py", line 1278, in _filter_action
    return action._allowed(request, datum) and row_matched
  File "horizon/horizon/tables/actions.py", line 136, in _allowed
    self.allowed(request, datum))
  File "horizon/openstack_dashboard/dashboards/project/networks/subnets/tables.py", line 103, in allowed
    if usages['subnets']['available'] <= 0:
KeyError: 'available'
Error while checking action permissions.

Steps to reproduce:
1) Set 'enable_quotas': False in OPENSTACK_NEUTRON_NETWORK
2) Restart Horizon
3) Go to Project/Networks
4) Click on any network
5) Note that you've got "Delete" button, but there is no "Create" button
6) Enable neutron quotas again and make sure that "Create" button appeared

There were already patch[1] for fixing this but looks like this piece of code has been missed.

[1] https://github.com/openstack/horizon/commit/5ba219acbfddb9b9308a75da361fda915ba61f37#diff-6f73ca5e50c3e694b8147669832912baR2152

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/302925

[OpenStack Infra (hudson-openstack)]

Change abandoned by Rob Cresswell (<email address hidden>) on branch: master
Review: https://review.openstack.org/302925
Reason: Abandoned due to inactivity. Feel free to restore if you wish to work on it

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/302925
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=8dc3e4324770bcc963cc213884861a563c2fd8e3
Submitter: Jenkins
Branch: master

commit 8dc3e4324770bcc963cc213884861a563c2fd8e3
Author: Paul Karikh <email address hidden>
Date: Thu Apr 7 19:04:36 2016 +0300

    Fix allowed() function for CreateSubnet

    If neutron quotas disabled, there is no usages['subnets']['available']
    So this check raises KeyError exception and makes "Create subnet"
    button dissapear.

    In addition, common codes in project.networks.tests related to
    this change are merged into a common method.

    Change-Id: I998c98c190fd4dc4039c7fb8ef7b1ef27bbeb863
    Closes-Bug: #1567529

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/horizon 12.0.0.0b2 development milestone.