return skip_rollback to true by default

devops-service/db/mongo/models/stack/stack_base.rb

@@ -122,7 +122,8 @@ module Devops
       end
 
       def skip_rollback?
-        launch_options['skip_rollback'] || false
+        result = launch_options['skip_rollback']
+        result.nil? ? true : result
       end
 
       class << self

devops-service/spec/models/stack/stack_ec2_spec.rb

@@ -79,8 +79,8 @@ RSpec.describe Devops::Model::StackEc2, type: :model do
       expect(stack.skip_rollback?).to be true
     end
 
-    it 'returns false by default' do
+    it 'returns true by default' do
-      expect(described_class.new.skip_rollback?).to be false
+      expect(described_class.new.skip_rollback?).to be true
     end
   end