NoMethodError: undefined method `merge_train' for nil:NilClass
https://sentry.gitlab.net/gitlab/gitlabcom/issues/1125967/
NoMethodError: undefined method `merge_train' for nil:NilClass
merge_trains/refresh_merge_requests_service.rb:63:in `following_merge_requests_from'
merge_request.merge_train.all_next.to_a.unshift(merge_request)
merge_trains/refresh_merge_requests_service.rb:50:in `unsafe_refresh'
following_merge_requests_from(merge_request).each do |merge_request|
merge_trains/refresh_merge_requests_service.rb:32:in `block in efficient_refresh'
unsafe_refresh(first_merge_request)
gitlab/batch_pop_queueing.rb:75:in `safe_execute'
yield all_args if block_given?
merge_trains/refresh_merge_requests_service.rb:30:in `efficient_refresh'
result = queue.safe_execute([merge_request.id], lock_timeout: 15.minutes) do |items|
...
(64 additional frame(s) were not displayed)
undefined method `merge_train' for nil:NilClass