My gemfile for my Ramaze (rack) app looks like this.
source 'http://rubygems.org'
ruby '1.9.3'
gem 'ramaze', "<= 2012.04.14" #old version
gem "innate", ">= 2012.03", "< 2012.11" #old version
gem 'rack', "<= 1.4.1"
gem 'sequel'
#if defined? ENV['RACK_ENV'] == 'production' then gem 'pg' else gem 'sqlite3' end
gem 'pg'
gem "sentry-raven", :git => "https://github.com/coderanger/raven-ruby.git"
gem 'bcrypt-ruby'
gem 'rdiscount'
gem 'redcarpet'
gem 'pony'
gem 'bacon'
gem 'koala'
gem 'stop_forum_spam'
#source 'http://mirror1.prod.rhcloud.com/mirror/ruby/'
#gem 'nokogiri'
#gem 'capybara'
As you can see, the pg gem is defined in it. However when I do a git push on Openshift, it installs every gem on my gem file EXCEPT for pg. I've done bundle install on my computer before a push with a force_clean_build file in the .openshift folder, and it didn't help.
I'm using the Sequel ORM and aren't even using a postgres database in my app, so changing the subject, I've no idea why it wants the pg gem in the first place.
Are you using Windows?
Try looking at this: https://bugzilla.redhat.com/show_bug.cgi?id=1126343