It actually does not work. A new gemfile is generated when building the gem for releasing. If you do it under 2.0 then `debugger` will not be in there. If you do it under 1.9 it will be in there.

try installing the gem under 1.9 and check your gemspec:
`cat /opt/boxen/rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/specifications/remote_files-2.1.0.gemspec | grep debugger`