我正在尝试设置我的红宝石环境，但不断收到以下 SystemStackError 错误消息：
$ bundle install
Warning: No private key present, creating unsigned gem.
Warning: No private key present, creating unsigned gem.
Warning: No private key present, creating unsigned gem.
Fetching gem metadata from http://rubygems.org/...........
Fetching additional metadata from http://rubygems.org/..
Resolving dependencies...
Using rake (11.1.2)
Using concurrent-ruby (1.1.3)
Using i18n (0.9.5)
SystemStackError: stack level too deep
An error occurred while installing multi_json (1.5.0), and Bundler cannot continue.
Make sure that `gem install multi_json -v '1.5.0'` succeeds before bundling.
但是，已经安装了multi_json v 1.5.0：
$ gem list | grep multi_json
multi_json (1.5.0)
$
有什么办法可以克服这个问题吗？