如何修复此恼人的警告以使用备用JSON库

Question

每当我运行heroku-toolbelt时，如何摆脱这个烦人的警告。

God@Heaven$heroku list
/usr/local/heroku/lib/heroku/command/stack.rb:64: warning: already initialized constant IN
/usr/local/heroku/lib/heroku/command/stack.rb:68: warning: already initialized constant OUT
[WARNING] MultiJson is using the default adapter (ok_json).We recommend loading a different JSON library to improve performance.
=== My Apps
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