Remove epic feature from Incidents

We extend support epic method to
filter out inicdent types.

ee/app/models/concerns/ee/issuable.rb

@@ -6,7 +6,7 @@ module EE
     extend ::Gitlab::Utils::Override
 
     def supports_epic?
-      is_a?(Issue) && project.group
+      is_a?(Issue) && !incident? && project.group.present?
     end
 
     def supports_health_status?

ee/app/views/shared/issuable/_sidebar_item_epic.haml

 - if issuable_sidebar[:supports_epic]
   - if issuable_sidebar[:features_available][:epics]
-    - unless @issuable.labels.map(&:title).include?('incident')
-      #js-vue-sidebar-item-epics-select{ data: { can_edit: can_admin_issue?.to_s, group_id: @project.group.id, issue_id: @issuable.id, epic_issue_id: @issuable.epic_issue&.id } }
+    #js-vue-sidebar-item-epics-select{ data: { can_edit: can_admin_issue?.to_s, group_id: @project.group.id, issue_id: @issuable.id, epic_issue_id: @issuable.epic_issue&.id } }
 
   - else
-    - unless @issuable.labels.map(&:title).include?('incident')
-      = render 'shared/promotions/promote_epics'
+    = render 'shared/promotions/promote_epics'

ee/spec/models/concerns/ee/issuable_spec.rb

@@ -29,4 +29,29 @@ RSpec.describe EE::Issuable do
       it_behaves_like 'matches_cross_reference_regex? fails fast'
     end
   end
+
+  describe '#supports_epic?' do
+    let(:group) { build_stubbed(:group) }
+    let(:project_with_group) { build_stubbed(:project, group: group) }
+    let(:project_without_group) { build_stubbed(:project) }
+
+    where(:issuable_type, :project, :supports_epic) do
+      [
+        [:issue, :project_with_group, true],
+        [:issue, :project_without_group, false],
+        [:incident, :project_with_group, false],
+        [:incident, :project_without_group, false],
+        [:merge_request, :project_with_group, false],
+        [:merge_request, :project_without_group, false]
+      ]
+    end
+
+    with_them do
+      let(:issuable) { build_stubbed(issuable_type, project: send(project)) }
+
+      subject { issuable.supports_epic? }
+
+      it { is_expected.to eq(supports_epic) }
+    end
+  end
 end