API returns a ruby hash and not json

Created by: sklise

On Opsworks:

curl 'http://HOST/api/v3/projects/PROJECT_ID/repository/tree?ref_name=master' -H 'Origin: http://localhost:3000' -H 'Accept-Encoding: gzip,deflate,sdch' -H 'PRIVATE-TOKEN: TOKEN' -H 'Accept-Language: en-US,en;q=0.8' -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.107 Safari/537.36' -H 'Accept: application/json, text/javascript, */*; q=0.01' -H 'Cache-Control: max-age=0'  -H 'Connection: keep-alive' -H 'DNT: 1' --compressed
{"message"=>"500 Internal Server Error"}

This is happening because there is no repository for this project yet. Not only does the error code not say this but it is a ruby hash and not json.