比如 rails
rubygems 的版本是 4.2.5.2 - February 29, 2016 taobao 源的版本是 4.2.5.1
➜ crm gem sources -a http://gems.ruby-china.org/ Error fetching http://gems.ruby-china.org/: bad response Bad Gateway 502 (http://120.52.72.56/gems.ruby-china.org/c3pr90ntcsf0/specs.4.8.gz)