bundle install每次都下载一堆rz，奇慢无比?报错

不懂ruby，搜索了一圈也没发现相关问题。

下载了一些ruby on rails的项目，按照官方文档bundle install安装依赖。配置了淘宝镜像仓库，在Gemfile行首配置：source 'https://ruby.taobao.org/'

运行bundle install的时候，输出如下：

HTTP GET https://bundler.rubygems.org/api/v1/dependencies
HTTP 200 OK
HTTP GET https://ruby.taobao.org/api/v1/dependencies
HTTP 404 Not Found
Fetching source index from https://ruby.taobao.org/
Need to query more than 500 gems. Downloading full index instead...
Fetching source index from https://rubygems.org/
HTTP GET https://ruby.taobao.org/quick/Marshal.4.8/coffee-rails-4.0.0.gemspec.rz
HTTP 302 Moved Temporarily
HTTP GET https://rubygems-china.oss.aliyuncs.com/quick/Marshal.4.8/coffee-rails-4.0.0.gemspec.rz
HTTP 200 OK
HTTP GET https://ruby.taobao.org/quick/Marshal.4.8/sass-rails-5.0.0.gemspec.rz
HTTP 302 Moved Temporarily
HTTP GET https://rubygems-china.oss.aliyuncs.com/quick/Marshal.4.8/sass-rails-5.0.0.gemspec.rz
HTTP 200 OK

简直要崩溃了，这是什么情况？bundler的依赖管理真的就这么稀烂吗？