AS::JSON Yaml backend sometimes do not honor AS:parse_json_times

ActiveSupport::VERSION::STRING "3.1.0.beta" (commit: 1408b942d9c2c131a1cdcab97f49d74ce84dae38)

>> ActiveSupport::JSON.backend = 'Yaml'
=> "Yaml"
>> ActiveSupport.parse_json_times = true
=> true
>> ActiveSupport::JSON.decode('{"timestamp":"2011-03-08T13:24:00Z"}')
=> {"timestamp"=>2011-03-08 13:24:00 UTC} #parsed, correct
>> ActiveSupport::JSON.decode('["2011-03-08T13:24:00Z"]')
=> ["2011-03-08T13:24:00Z"] #not parsed, incorrect!
>> ActiveSupport.parse_json_times = false
=> false
>> ActiveSupport::JSON.decode('{"timestamp":"2011-03-08T13:24:00Z"}')
=> {"timestamp"=>2011-03-08 13:24:00 UTC} #parsed, incorrect!
>> ActiveSupport::JSON.decode('["2011-03-08T13:24:00Z"]')
=> ["2011-03-08T13:24:00Z"] #not parsed, correct

FYI, JSONGem backend works correctly.

>> ActiveSupport::JSON.backend = 'JSONGem'
=> "JSONGem"
>> ActiveSupport.parse_json_times = true
=> true
>> ActiveSupport::JSON.decode('{"timestamp":"2011-03-08T13:24:00Z"}')
=> {"timestamp"=>Tue, 08 Mar 2011 13:24:00 +0000} #parsed, correct
>> ActiveSupport::JSON.decode('["2011-03-08T13:24:00Z"]')
=> [Tue, 08 Mar 2011 13:24:00 +0000] #parsed, correct
>> ActiveSupport.parse_json_times = false
=> false
>> ActiveSupport::JSON.decode('{"timestamp":"2011-03-08T13:24:00Z"}')
=> {"timestamp"=>"2011-03-08T13:24:00Z"} #not parsed, correct
>> ActiveSupport::JSON.decode('["2011-03-08T13:24:00Z"]')
=> ["2011-03-08T13:24:00Z"] #not parsed, correct