beefproject/beef — pull request #1045 by evoltech (2014-09-14 23:34:03+00:00)
Title: This is needed for BeEF to work on Ubuntu Trusty 64bit ruby-1.9.3-p448 (...

...via rvm)

Without adding this you will get the errors as reported here: http://stackoverflow.com/questions/25779927/segmentation-fault-when-compile-assets-in-rails