http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/6131

The above fix seems to still be needed in ruby-1.8.4, to fix the
following problem:

irb(main):005:0> t = Time.now.to_i
=> 1137525209
irb(main):006:0> y t
--- !ruby/object:Bignum 1137525209
=> nil
irb(main):007:0> t.to_yaml
=> "--- !ruby/object:Bignum 1137525209\n"
irb(main):008:0> YAML.load(t.to_yaml)
TypeError: allocator undefined for Bignum
        from /usr/local/lib/ruby/1.8/yaml.rb:133:in `transfer'
        from /usr/local/lib/ruby/1.8/yaml.rb:133:in `load'
        from (irb):8

-- 
      vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407