undefined method `source_index' for Gem:Module

[cevaris]

Getting an error when generating a new project

My rvm points to /opt/twitter/rvm/.

ruby (master) ~࿔ newgem codexrb
undefined method `source_index' for Gem:Module
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:284:in `generator_full_paths'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:272:in `each'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:171:in `to_a'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:171:in `block in cache'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:171:in `each'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:171:in `inject'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:171:in `cache'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:152:in `lookup'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/lookup.rb:165:in `instance'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/rubigen-1.5.8/lib/rubigen/scripts.rb:32:in `run'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/gems/newgem-1.5.3/bin/newgem:28:in `<top (required)>'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/bin/newgem:23:in `load'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/bin/newgem:23:in `<main>'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/bin/ruby_executable_hooks:15:in `eval'
  /opt/twitter/rvm/gems/ruby-2.0.0-p645/bin/ruby_executable_hooks:15:in `<main>'
ruby (master) ~࿔ ruby -v
ruby 2.0.0p645 (2015-04-13 revision 50299) [x86_64-darwin14.4.0]