Pretty big/breaking change in the new Ruby 2.0.0 patch level (p0 => p195).

twoby.rb

def keyword_fun arg = nil, **options
  [arg, options]
end
keyword_fun hello: 'world', 'goodnight' => 'moon'

# Ruby 2.0.0p0
# => [nil, {:hello=>"world", "goodnight"=>"moon"}]

# Ruby 2.0.0p195
# => [{"goodnight"=>"moon"}, {:hello=>"world"}]

"Fixed" here:

https://bugs.ruby-lang.org/projects/ruby-200/repository/revisions/40381/diff
https://bugs.ruby-lang.org/issues/8260

nasty bug. But, tbh I would never write a hash that mixed old and new styles like that.

Yeah, it's just more surprising than anything else. You can no longer pass a HashWithIndifferentAccess as keyword arguments, or use **options to extract the last hash from *args (you have to use Array#pop or Array#extract_options!, as before).