bugsnag/bugsnag-ruby — pull request #73 by ConradIrwin (2013-12-27 00:21:55+00:00)
Title: Use cause from ruby 2.1 [https://bugs.ruby-lang.org/issues/8257]

See also http://devblog.avdi.org/2013/12/25/exception-causes-in-ruby-2-1/