Fix validation to allow updates to description/color of project label

app/models/project_label.rb

@@ -14,7 +14,7 @@ def to_reference(target_project = nil, format: :id)
   private
 
   def title_must_not_exist_at_group_level
-    return unless group.present?
+    return unless group.present? && title_changed?
 
     if group.labels.with_title(self.title).exists?
       errors.add(:title, :label_already_exists_at_group_level, group: group.name)

spec/models/project_label_spec.rb

@@ -40,6 +40,16 @@
 
         expect(label.errors[:title]).to be_empty
       end
+
+      it 'does not returns error when title does not change' do
+        project_label = create(:label, project: project, name: 'Security')
+        create(:group_label, group: group, name: 'Security')
+        project_label.description = 'Security related stuff.'
+
+        project_label.valid?
+
+        expect(project_label  .errors[:title]).to be_empty
+      end
     end
   end