Comment 13 for bug 1440046

Fix doesn't solve the main problem.

Test cases that I did:
Case 1:
1) Install master
2) Create new plugin with version 1.0.0
3) Install plugin at the master node
4) Create new env
5) Navigate to the Other Settings tab
6) DO NOT enable plugin at the cluster
7) Remove plugin from the master node

Expected result:
Plugin is successfully removed.
Actual result:
An error message is shown:
[root@nailgun ~]# fuel plugins --remove vip_plugin==1.0.0
400 Client Error: Bad Request (Can't delete plugin which is enabled for some environment.)

Case 2:
1) Perform steps 1-4 from case 1
2) Create another plugin with the same name but with higher version, for example: 2.0.0
3) Install new plugin at the master node
4) Navigate to the Other Settings tab
6) Enable plugin at the cluster (here we have a choice plugin with which version we need to enable, let's enable 1.0.0)
7) Remove plugin 2.0.0 from the master node
8) Enable plugin 2.0.0 at the cluster
9) Remove plugin 1.0.0 from the master node

Expected result:
If we enable some version of plugin at the UI we can delete another version from master node.

Actual result:
Plugin could't be deleted even we choose another version of that plugin at UI:
[root@nailgun ~]# fuel plugins --remove vip_plugin==2.0.0
400 Client Error: Bad Request (Can't delete plugin which is enabled for some environment.)
[root@nailgun ~]# fuel plugins --remove vip_plugin==1.0.0
400 Client Error: Bad Request (Can't delete plugin which is enabled for some environment.)

Fuel iso #203 was used