Reproduced

app/views/projects/pipeline_schedules/_pipeline_schedule.html.haml

@@ -4,7 +4,8 @@
       = pipeline_schedule.description
     %td.branch-name-cell
       = icon('code-fork')
-      = link_to pipeline_schedule.ref, project_ref_path(@project, pipeline_schedule.ref), class: "ref-name"
+      - if pipeline_schedule.ref.present?
+        = link_to pipeline_schedule.ref, project_ref_path(@project, pipeline_schedule.ref), class: "ref-name"
     %td
       - if pipeline_schedule.last_pipeline
         .status-icon-container{ class: "ci-status-icon-#{pipeline_schedule.last_pipeline.status}" }

spec/features/projects/pipeline_schedules_spec.rb

@@ -65,6 +65,17 @@ feature 'Pipeline Schedules', :feature do
         expect(page).not_to have_content('pipeline schedule')
       end
     end
+
+    context 'when ref is NULL' do
+      before do
+        pipeline_schedule.update_attribute(:ref, nil)
+        visit_pipelines_schedules
+      end
+
+      it 'shows a list of the pipeline schedules with empty ref column' do
+        expect(first('.branch-name-cell').text).to eq('')
+      end
+    end
   end
 
   describe 'POST /projects/pipeline_schedules/new', js: true do
@@ -108,6 +119,19 @@ feature 'Pipeline Schedules', :feature do
 
       expect(page).to have_content('my brand new description')
     end
+
+    context 'when ref is NULL' do
+      before do
+        pipeline_schedule.update_attribute(:ref, nil)
+        edit_pipeline_schedule
+      end
+
+      it 'shows the pipeline schedule with default ref' do
+        page.within('.git-revision-dropdown-toggle') do
+          expect(first('.dropdown-toggle-text').text).to eq('master')
+        end
+      end
+    end
   end
 
   def visit_new_pipeline_schedule