Use existing pipeline stage if stage already exists

app/models/commit_status.rb

@@ -192,12 +192,20 @@ class CommitStatus < ActiveRecord::Base
   private
   def ensure_pipeline_stage!
-    attributes = { name: stage, pipeline: pipeline, project: project }
-
-    Ci::Stage.create!(attributes).tap do |stage|
+    (find_stage || create_stage!).tap do |stage|
       self.stage_id = stage.id
       yield stage
     end
   end
+
+  def find_stage
+    pipeline.stages.find_by(name: stage)
+  end
+
+  def create_stage!
+    Ci::Stage.create!(name: stage,
+                      pipeline: pipeline,
+                      project: project)
+  end
 end

spec/models/commit_status_spec.rb

@@ -499,6 +499,29 @@ describe CommitStatus do
       end
     end
+    context 'when commit status does not have stage but it exists' do
+      let!(:stage) do
+        create(:ci_stage_entity, project: project,
+                                 pipeline: pipeline,
+                                 name: 'test')
+      end
+
+      let(:commit_status) do
+        create(:commit_status, project: project,
+                               pipeline: pipeline,
+                               name: 'rspec',
+                               stage: 'test',
+                               status: :success)
+      end
+
+      it 'uses existing stage' do
+        expect { commit_status }.not_to change { Ci::Stage.count }
+
+        expect(commit_status.stage_id).to eq stage.id
+        expect(stage.reload.status).to eq commit_status.status
+      end
+    end
+
     context 'when commit status is being imported' do
       let(:commit_status) do
         create(:commit_status, name: 'rspec', stage: 'test', importing: true)