id for radio_button behavior

Hello,

is the following behevior intentional?

Loading development environment (Rails 2.3.2)
>> irb helper
>> @foo = "foo"
>> puts(radio_button("foo", "hash", true))
<input id="foo_hash_true" name="foo[hash]" type="radio" value="true" />
                   ^^^^^
>> puts(radio_button("foo", "hash", false))
<input id="foo_hash_false" name="foo[hash]" type="radio" value="false" />
                   ^^^^^^

Loading development environment (Rails 2.3.3)
>> irb helper
>> @foo = "foo"
>> puts(radio_button("foo", "hash", true))
<input id="foo_hash_true" name="foo[hash]" type="radio" value="true" />
                   ^^^^^ same as 2.3.2
>> puts(radio_button("foo", "hash", false))
<input id="foo_hash" name="foo[hash]" type="radio" value="false" />
                   ? different from 2.3.2

Yes, I know that the 3rd argument should be string, and
this comes from around add_default_name_and_id_for_value.

Thanks,