Active Record 关联中has_one中的foreign_key使用无效

https://ruby-china.github.io/rails-guides/association_basics.html#has-one-association-reference
%E5%BD%93%E5%89%8D%E4%BD%BF%E7%94%A8%E7%9A%84rails%204.2.1
%E6%8C%89%E6%95%99%E7%A8%8B%E4%B8%AD%E5%9C%A8has_one%E4%B8%AD%E5%8A%A0foreign_key%E6%98%AF%E4%B8%8D%E7%94%9F%E6%95%88%E7%9A%84%EF%BC%8C%E5%9C%A8belongs_to%E4%B8%AD%E5%8A%A0foreign_key%E6%89%8D%E7%94%9F%E6%95%88