rails/rails — pull request #6119 by romanvbabenko (2012-05-02 11:04:14+00:00)
Title: Gem cont presence checking has been removed

Rails boot.rb permanently depends from rubygems.
https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/app/templates/config/boot.rb#L1

Checking Gem cont presence doe's not make sense.