Demonstrate that psych/libyaml is borked

psych_is_borked.rb

require 'rubygems'

# Switch the following two lines to see the bug in the psych that ships with Ruby
# Comment out both to see the default YAML parsing behaviour
gem 'psych'
# require 'psych'

require 'yaml'
require 'erb'

puts "RUBY_VERSION: #{RUBY_VERSION}"
puts "YAML::VERSION: #{YAML::VERSION}"

yaml = <<-YAML
common: &common
  adapter: postgresql

development:
  <<: *common
  database: example_development

test: &test
  <<: *common
  database: example_test

production:
  <<: *common
  database: example_production

YAML

config = YAML::load(yaml)

development = config["development"]
database = development["database"]

puts "development[database]: #{database.inspect}"

Psych that ships with Ruby

RUBY_VERSION: 1.9.2
YAML::VERSION: 1.0.0
development[database]: nil

YAML that ships with Ruby

RUBY_VERSION: 1.9.2
YAML::VERSION: 0.60
development[database]: "example_development"

Psych 1.1.1 gem

RUBY_VERSION: 1.9.2
YAML::VERSION: 0.60
development[database]: "example_development"