Running start.jar uses ruby 1.8.7, doesn't work with new hash syntax in session_store.rb

[debugging]

I'm running rvm, and my default ruby is 1.9.3.
When I run the jar that jetpack produces, I get the below error:

An exception happened during JRuby-Rack startup|/Users/snad/dev/sources/jruby/jettytest/jettytest/config/initializers/session_store.rb:3: syntax error, unexpected ':'||Jettytest::Application.config.session_store :cookie_store, key: '_jettytest_session'| ^|--- System|jruby 1.6.5.1 (ruby-1.8.7-p330) (2011-12-27 1bf37c2) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_51) [darwin-x86_64-java]|Time: Thu Jul 04 00:02:18 -0400 2013|Server: jetty/7.4.5.v20110725|```

Why is it using ruby 1.8.7? When I ran 'bundle exec jetpack .' I was using rvm with ruby-1.9.3-p392

I am using jruby 1.7.4 also.