Right now, Ember's gemspec points to a specific version of Handlebars. If Handlebars is following SemVer, we can probably change it to "~> 1.0". This would mean no modifying the Ember gemspec. Since Ember uses Bundler, we could actually have the user just add the following to the Ember Gemfile:

    gem "handlebars-source", :path => "path/to/handlebars/dist/components"

I'm open to adding an ENV var conditional to the Ember Gemfile to make this easier. Something along the lines of:

    if ENV['HANDLEBARS_PATH']
       gem "handlebars-source", :path => ENV['HANDLEBARS_PATH']+'/dist/components'
    end