Allow usage of severity quickaction on create

Changelog: changed

lib/gitlab/quick_actions/issuable_actions.rb

@@ -246,14 +246,20 @@ module Gitlab
         params '1 / S1 / Critical'
         types Issue
         condition do
-          quick_action_target.supports_severity?
+          !quick_action_target.persisted? || quick_action_target.supports_severity?
         end
         parse_params do |severity|
           find_severity(severity)
         end
         command :severity do |severity|
+          next unless quick_action_target.supports_severity?
+
           if severity
-            ::Issues::UpdateService.new(project: quick_action_target.project, current_user: current_user, params: { severity: severity }).execute(quick_action_target)
+            if quick_action_target.persisted?
+              ::Issues::UpdateService.new(project: quick_action_target.project, current_user: current_user, params: { severity: severity }).execute(quick_action_target)
+            else
+              quick_action_target.build_issuable_severity(severity: severity)
+            end
 
             @execution_message[:severity] = _("Severity updated to %{severity}.") % { severity: severity.capitalize }
           else

spec/services/quick_actions/interpret_service_spec.rb

@@ -2096,6 +2096,19 @@ RSpec.describe QuickActions::InterpretService do
         end
       end
 
+      context 'when quick action is used on creation' do
+        let(:content) { '/severity s3' }
+        let(:issuable) { build(:incident, project: project) }
+
+        it_behaves_like 'updates the severity', 'medium'
+
+        context 'issuable does not support severity' do
+          let(:issuable) { build(:issue, project: project) }
+
+          it_behaves_like 'failed command', ''
+        end
+      end
+
       context 'severity given with S format' do
         let(:content) { '/severity s3' }