Object and method in the Kernel module

Hi,
I'm trying to make jruby behave correctly with regard to global functions.
Right now the following code


nil.puts 'toto'
in jruby outputs toto, this seems logical since nil is an Object, in fact
it is the only instance of NilClass which derives from Object and which
includes
the Kernel module which defines the puts method.

However by trying with ruby I get the following:
-e:1: undefined method `puts' for nil (NameError)
this doesn't make sense, especially since
Object.new.puts 'toot'
gives
NameError: private method `puts' called for #<Object:0x10098120>
why don't I get the same error for nil as for Object.new, what is the rule
here
and how should jruby behave?
Benoit