NoMethodError: undefined method `namespace' for nil:NilClass

https://sentry.gitlab.net/gitlab/gitlabcom/issues/1185334/

NoMethodError: undefined method `namespace' for nil:NilClass
  merge_request_presenter.rb:72:in `cherry_pick_in_fork_path'
    namespace_key: current_user.namespace.id,
  merge_request_poll_widget_entity.rb:129:in `block in <class:MergeRequestPollWidgetEntity>'
    presenter(merge_request).cherry_pick_in_fork_path
  grape_entity/entity.rb:494:in `instance_exec'
    instance_exec(object, &block)
  grape_entity/entity.rb:494:in `exec_with_object'
    instance_exec(object, &block)
  grape_entity/exposure/block_exposure.rb:10:in `value'
    entity.exec_with_object(options, &@block)
...
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NoMethodError: undefined method `namespace' for nil:NilClass

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