Fix creating a group after validation message 'already exists'

[hstastna]

Fixes issue:
#5140
BZ:
https://bugzilla.redhat.com/show_bug.cgi?id=1690889

What:
Fix creating a group (Configuration > Access Control > Groups) for the second time, after a validation message like 'Description is not unique...' appears.

Steps to reproduce:

1. Go to Configuration > Access Control > Groups accordion
2. Configuration > Add a new Group and create a group
3. Try to create another group with the same description as from step 2
   => error flash message occurs
4. Follow the message and change the description of the new group, press Add button
   => nothing happens in the UI + error:

[----] I, [2019-03-19T17:28:55.994747 #11522:2ad94de6c2f0]  INFO -- : Started POST "/ops/rbac_group_edit?button=add" for ::1 at 2019-03-19 17:28:55 +0100
[----] I, [2019-03-19T17:28:56.033217 #11522:2ad94de6c2f0]  INFO -- : Processing by OpsController#rbac_group_edit as JS
[----] I, [2019-03-19T17:28:56.033346 #11522:2ad94de6c2f0]  INFO -- :   Parameters: {"button"=>"add"}
[----] F, [2019-03-19T17:28:56.045202 #11522:2ad94de6c2f0] FATAL -- : Error caught: [NoMethodError] undefined method `empty?' for nil:NilClass
/home/hstastna/manageiq/manageiq-ui-classic/app/controllers/ops_controller/ops_rbac.rb:1377:in `rbac_group_validate?'
/home/hstastna/manageiq/manageiq-ui-classic/app/controllers/ops_controller/ops_rbac.rb:674:in `rbac_edit_save_or_add'
/home/hstastna/manageiq/manageiq-ui-classic/app/controllers/ops_controller/ops_rbac.rb:92:in `rbac_group_edit'

TODO:

• specs

Note:
This issue is also present in the latest gaprindashvili and hammer branches.

Details:
In rbac_group_set_record_vars method, in https://github.com/ManageIQ/manageiq-ui-classic/pull/5354/files#diff-8078c760e06b820719715450b2a112e0L1203, @edit[:new][:filter_expression] was set to nil, so then in rbac_group_validate? method, in https://github.com/ManageIQ/manageiq-ui-classic/pull/5354/files#diff-8078c760e06b820719715450b2a112e0L1377 a problem occurred, because empty? does not work with nil, obviously. Also setting @edit[:new][:filter_expression] to nil is in conflict with what is in https://github.com/ManageIQ/manageiq-ui-classic/pull/5354/files#diff-8078c760e06b820719715450b2a112e0L1111 where we set it to {}.

---

Step 3 from steps to reproduce:

Before: (nothing happens after clicking on Add button, test2 group is not saved properly)

After:(test2 group saved without any problems, flash message appears)

[hstastna]

@miq-bot add_label bug, hammer/yes

[miq-bot]

Checked commit hstastna@7090474 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 0 offenses detected
Everything looks fine. 👍

[hstastna]

@lpichler, what do you think about the fix? Thanks! 🎇

[hstastna]

@miq-bot add_label gaprindashvili/yes

[simaishi]

Hammer backport details:

$ git log -1
commit f3a5226f87bf42c6cde7e5f7db5674efe1ee1032
Author: Milan Zázrivec <[email protected]>
Date:   Wed Mar 20 10:25:20 2019 +0100

    Merge pull request #5354 from hstastna/Cannot_create_group_already_exist
    
    Fix creating a group after validation message 'already exists'
    
    (cherry picked from commit 8b2f589ea5d0775dabd1667012b9f36fab8534cb)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1712440