I'm wondering if its really necessary to check for `RACK_ENV`. As the RAILS_ENV will overrule the RACK_ENV anyways.

    $ RACK_ENV=test rs
    => Booting Unicorn
    => Rails 3.2.13 application starting in development on http://0.0.0.0:3000
    => Call with -d to detach
    => Ctrl-C to shutdown server
    Connecting to database specified by database.yml
    RACK_ENV: "development"
    listening on addr=0.0.0.0:3000 fd=28