Fix for bug in Rails 2.3's vendored BlankSlate.

environment.rb

config.gem "toml", :version => "0.0.4"
class BlankSlate
  class << self
    # Hide the method named +name+ in the BlankSlate class.  Don't
    # hide +instance_eval+ or any method beginning with "__".
    def hide(name)
      # CHANGED: if instance_methods.include?(name.to_s) and
      if instance_methods.include?(name.to_sym) and
        name !~ /^(__|instance_eval)/
        @hidden_methods ||= {}
        @hidden_methods[name.to_sym] = instance_method(name)
        undef_method name
      end
    end
  end
end
require "toml"
# Initializes the Context class so that all its `hide`s get called.
_ = Parslet::Transform::Context.new([])