Why this Action Pack test case failed with JRuby 1.0.3?

Hi,

I was running the test cases from Rails 1.2.6 Action Pack. The full
text of test is here. There is one case like this:

def test_process_with_session_arg
    process :no_op, nil, { 'string' => 'value1', :symbol => 'value2' }
    assert_equal 'value1', session['string']
    assert_equal 'value1', session[:string]
    assert_equal 'value2', session['symbol']
    assert_equal 'value2', session[:symbol]
  end

I was using JRuby 1.0.3 on a UNIX platform, to my surprised this case
only first assert passed and all other three failed. The error message
says "<value1> expected but was <nil>"

After I changed ":symbol => 'value2' " to " 'symbol' => 'value2' ",
assert 1 and 3 passed but 2 and 4 were always failed. The error
message was the same.

However all these tests were passed on my Gentoo box with JRuby 1.0.3.
The JVM are the same Java5.0.

What could be wrong for it? Theoratically JRuby is platform
independent and I was using the same version of JVM on both UNIX and
Gentoo. Why 'symbol' works but :symbol failed?

Thanks,
Song Ma