A stop action support for an already deployed cluster

I want to stop deploying of an already deployed cluster with changed config.

Steps to reproduce:
1) Setup Fuel
2) Create a new cluster
3) Deploy the cluster
4) After successful deploying change some settings to enable Deploy changes button
5) Start a new deployment of the cluster
6) Stop deployment process

Expected behavior:
The deployment is stopped

Actual behavior:
There is an error message: "Stop action is forbidden for the cluster"

Since there is no workaround I set Importance to Critical

Fuel used:
[root@nailgun ~]# shotgun2 short-report
cat /etc/fuel_build_id:
 213
cat /etc/fuel_build_number:
 213
cat /etc/fuel_release:
 9.0
cat /etc/fuel_openstack_version:
 mitaka-9.0
rpm -qa | egrep 'fuel|astute|network-checker|nailgun|packetary|shotgun':
 fuel-release-9.0.0-1.mos6338.noarch
 fuel-misc-9.0.0-1.mos8298.noarch
 python-packetary-9.0.0-1.mos131.noarch
 fuel-openstack-metadata-9.0.0-1.mos8654.noarch
 fuel-provisioning-scripts-9.0.0-1.mos8654.noarch
 python-fuelclient-9.0.0-1.mos309.noarch
 fuel-9.0.0-1.mos6338.noarch
 fuel-nailgun-9.0.0-1.mos8654.noarch
 rubygem-astute-9.0.0-1.mos738.noarch
 fuel-library9.0-9.0.0-1.mos8298.noarch
 fuel-agent-9.0.0-1.mos272.noarch
 fuel-ui-9.0.0-1.mos2659.noarch
 fuel-setup-9.0.0-1.mos6338.noarch
 nailgun-mcagents-9.0.0-1.mos738.noarch
 shotgun-9.0.0-1.mos87.noarch
 network-checker-9.0.0-1.mos72.x86_64
 fuel-bootstrap-cli-9.0.0-1.mos272.noarch
 fuel-migrate-9.0.0-1.mos8298.noarch
 fuelmenu-9.0.0-1.mos268.noarch
 fuel-notify-9.0.0-1.mos8298.noarch
 fuel-ostf-9.0.0-1.mos924.noarch
 fuel-mirror-9.0.0-1.mos131.noarch
 fuel-utils-9.0.0-1.mos8298.noarch