仍然有这个错误，这个文件确实是存在的

~ → gem sources --add https://ruby.taobao.org/ -V

GET https://ruby.taobao.org/specs.4.8.gz 302 Moved Temporarily Error fetching https://ruby.taobao.org/: no such name (https://ruby.taobao.org/specs.4.8.gz)