Fix Staging::Workflow#unassigned method

we don't need to consider staged requests as the current workflow will remove
them anyway from the stageable association.

src/api/app/models/staging/workflow.rb

@@ -36,7 +36,7 @@ def ready_to_stage
   before_update :update_staging_projects_managers_group
 
   def unassigned_requests
-    target_of_bs_requests.stageable.where.not(id: excluded_requests | staged_requests)
+    target_of_bs_requests.stageable.where.not(id: excluded_requests)
   end
 
   def ready_requests

src/api/spec/models/staging/workflow_spec.rb

@@ -3,13 +3,14 @@
 RSpec.describe Staging::Workflow, type: :model do
   let(:project) { create(:project_with_package, name: 'MyProject') }
   let(:staging_workflow) { create(:staging_workflow_with_staging_projects, project: project) }
+  let(:group) { staging_workflow.managers_group }
   let(:staging_project) { staging_workflow.staging_projects.first }
   let(:source_project) { create(:project, name: 'source_project') }
   let(:target_package) { create(:package, name: 'target_package', project: project) }
   let(:source_package) { create(:package, name: 'source_package', project: source_project) }
   let(:bs_request) do
     create(:bs_request_with_submit_action,
-           request_state: 'review',
+           request_state: :review,
            target_project: project.name,
            target_package: target_package.name,
            source_project: source_project.name,
@@ -23,13 +24,19 @@
       it { expect(subject).to be_empty }
     end
 
-    context 'with requests but not in staging projects' do
+    context 'with requests without reviews by the staging managers group' do
       before { bs_request }
 
+      it { expect(subject).to be_empty }
+    end
+
+    context 'with requests with reviews by the staging managers group' do
+      let!(:review) { create(:review, by_group: group.title, bs_request: bs_request) }
+
       it { expect(subject).to contain_exactly(bs_request) }
     end
 
-    context 'with requests but all of them are in staging projects' do
+    context 'with requests but all of them are already assigned' do
       before do
         bs_request.staging_project = staging_project
         bs_request.save
@@ -39,12 +46,15 @@
     end
 
     context 'with requests and some are in staging projects and some not' do
+      let(:review2) { create(:review, by_group: group.title) }
       let!(:bs_request_2) do
         create(:bs_request_with_submit_action,
                target_project: project.name,
                target_package: target_package.name,
                source_project: source_project.name,
-               source_package: source_package.name)
+               source_package: source_package.name,
+               reviews: [review2],
+               state: :review)
       end
 
       before do