Multiple values for a block parameter warning

I'm seeing this warning on a Rails 3.2.11 app using Rack 1.4.4 for every request after upgrading Rails and Rack

/Users/bsb/.rvm/gems/jruby-1.7.0@jefe/gems/rack-1.4.4/lib/rack/utils.rb:387 warning: multiple values for a block parameter (2 for 1)

I'm also and could be completely unrelated seeing the number 7699 render at the top of all my pages as in

7699
<!DOCTYPE html>
<html lang="en">

Which I assume is also Rack Response related.

My Gemfile:

source 'https://rubygems.org'

gem 'rails', '3.2.11'
gem 'activerecord-jdbcsqlite3-adapter'
gem 'trinidad' 
gem 'rails_admin' 
gem 'devise',   '~> 2.1.3'
gem 'jquery-rails'
gem 'octokit' 
gem 'activerecord-tableless'
gem 'carrierwave'
gem 'friendly_id',   '~> 4.0.9'  
gem 'client_side_validations'
gem 'smt_rails', '~> 0.2.4'
gem 'jbuilder', '~> 0.9.0'
gem 'draper', '~> 1.0.0'

group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'
  gem 'therubyrhino'
  gem 'uglifier', '>= 1.0.3'  
  gem 'less-rails'
  gem 'twitter-bootstrap-rails', '2.2.0'
end  

group :development, :test do
  gem 'rspec-rails'   
  gem 'quiet_assets'
  gem 'foreman'
  #gem 'posix-spawn'
  gem 'thin'
end

group :test do
  gem 'capybara'
  gem 'factory_girl_rails'
  gem 'shoulda-matchers'
end

# the javascript engine for execjs gem
platforms :jruby do
  group :assets do
    gem 'therubyrhino'
  end
end

jruby / jruby-rack

Multiple values for a block parameter warning #146

My Gemfile: