Do not try to copy weight events when promoting an issue

When promoting an issue to an epic we copy over as much
information as possible, but we need to skip weight events as
epics do not support weights.

app/services/issuable/clone/attributes_rewriter.rb

@@ -56,7 +56,7 @@ module Issuable
       end
 
       def copy_resource_weight_events
-        return unless original_entity.respond_to?(:resource_weight_events)
+        return unless both_respond_to?(:resource_weight_events)
 
         copy_events(ResourceWeightEvent.table_name, original_entity.resource_weight_events) do |event|
           event.attributes

ee/changelogs/unreleased/215549-skip-copying-weight-events-when-promoting-issue.yml

+---
+title: Do not try to copy issue weight events when promoting an issue to epic
+merge_request: 43891
+author:
+type: fixed

ee/spec/services/ee/issuable/clone/attributes_rewriter_spec.rb

@@ -39,6 +39,16 @@ RSpec.describe Issuable::Clone::AttributesRewriter do
           subject.execute
         end
       end
+
+      context 'when issue has weight events' do
+        it 'ignores copying weight events' do
+          create_list(:resource_weight_event, 2, issue: original_issue)
+
+          expect(subject).not_to receive(:copy_events).with(ResourceWeightEvent.table_name, any_args)
+
+          expect { subject.execute }.not_to change { ResourceWeightEvent.count }
+        end
+      end
     end
   end
 end