[racket] ill-formed code (unexpected graph structure) with custom #lang

Hello,

Racket seems to have an issue with programs compiled by raco make:


$ racket test.slon
OK

$ raco make test.slon
$ racket test.slon
compiled/test_slon.zo: : read (compiled): ill-formed code (unexpected 
graph structure)
   context...:
    standard-module-name-resolver

$ rm compiled/test_slon.zo
$ racket test.slon
OK

"slon" is a custom language implemented in Racket. I am not sure if it 
matters. Anyway, as soon as I delete compiled/test_slon.zo, it starts to 
work, even with the "slon/compiled" and "slon/lang/compiled" directories 
left intact.

The test_slon.zo file is 3 KB, the program does nearly nothing, and I 
have no idea what causes the error. Here is the compiled file (encoded 
in base64):

http://pastebin.com/r1kCi5ki

I am having this trouble in Racket 6.1.1.6, and had it with prior 
versions (but not all of them -- some time ago everything worked as 
expected, but I forgot which version that was).

Is there anything I can do to help to track down the bug?

Best regards,

Dmitry