rails/rails — pull request #8234 by kentaro (2012-11-16 05:28:55+00:00)
Title: Updated dependency on bundler to ~> 1.2.2

Bundler <= 1.2.1 and Ruby 2.0.0 can raise an error since the commit below (incompatible change was added to Error class):

https://bugs.ruby-lang.org/projects/ruby-trunk/repository/revisions/37292

I think it's better for Rails 4 to update the dependency on bundler to ~> 1.2.2 toward the next coming Ruby 2.0.0, in advance.