Mutex#synchronize block params oddity in 2.0

mutex.rb

require 'thread'

Mutex.new.synchronize do |*args|
  p RUBY_VERSION => args
end

output.1.9.txt

$ ruby -v
ruby 1.9.3p194 (2012-04-20 revision 35410) [i686-linux]
$ ruby mutex.rb 
{"1.9.3"=>[]}

output.2.0.txt

$ ruby -v
ruby 2.0.0p0 (2013-02-24 revision 39474) [i686-linux]
$ ruby mutex.rb 
{"2.0.0"=>[nil]}