Here is the bug-report link. In that post I use a more redundant example, but the idea is the same.
[Me to Matthew Flatt]
Thanks for your answer! But I am more confused:
1 Both the newest version of Chez/Ypsilon Scheme give [Do you catch me?] output.
2 Both of them claim that their implementation confirm to the newest r6rs standard.
3 Are they all wrong? Or is Racket intend not to compatible with r6rs in this point(If the answer is 'yes', what're the benefits)?
[Matthew Flatt to Me]
I don't think that R6RS is clear on the point of splicing `begin's or
on the continuation of a module body. Even within what is specified,
it's possible that Racket's R6RS implementation doesn't handle `begin'
spliciing according to the standard.
Meanwhile, as you say, `racket' is a different language, and we've
chosen a simpler and more consistent rule for `begin' splicing (i.e.,
always splice). The `racket' language also takes advantage of prompts
to enable local reasoning about continuations in a module (i.e., you
don't have to wonder about the continuation of a module body's
evaluation, which is difficult to specify).