Make sure the algorithm did exclude gaps

spec/models/ci/pipeline_spec.rb

@@ -126,7 +126,7 @@ describe Ci::Pipeline, models: true do
     let(:current) { Time.now.change(usec: 0) }
     let(:build) { create_build('build1', current, 10) }
     let(:build_b) { create_build('build2', current, 20) }
-    let(:build_c) { create_build('build3', current + 40, 20) }
+    let(:build_c) { create_build('build3', current + 50, 10) }
 
     describe '#duration and #pending_duration' do
       before do
@@ -156,7 +156,7 @@ describe Ci::Pipeline, models: true do
         pipeline.reload
 
         expect(pipeline.duration).to eq(40)
-        expect(pipeline.pending_duration).to eq(35)
+        expect(pipeline.pending_duration).to eq(25)
       end
     end