Deploy to heroku: what's causing the problem with nokogiri?

Question

Heroku

When going to the page, an error is written in the log:

2014-02-24T18:43:37.017129+00:00 app[web.1]: Started GET "/pageresult" for 176.117.161.7 at 2014-02-24 18:43:37 +0000
2014-02-24T18:43:37.021831+00:00 app[web.1]: Completed 500 Internal Server Error in 4ms
2014-02-24T18:43:37.021831+00:00 app[web.1]: Completed 500 Internal Server Error in 4ms
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]: NameError (uninitialized constant JobController::Net):
2014-02-24T18:43:37.025549+00:00 app[web.1]:   app/controllers/job_controller.rb:51:in `pageresult'
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]: NameError (uninitialized constant JobController::Net):
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]:
2014-02-24T18:43:37.025549+00:00 app[web.1]:   app/controllers/job_controller.rb:51:in `pageresult'