[racket] Strange error 5.1.0.2 define-runtime-path

I was going to experiment with places for parallelism and I have
compiled from source to support it. Then I've encountered a very strange
bug that does not happen with 5.1

;;test.rkt
#lang racket
(require "def.rkt")

(displayln dyn-def)

;;def.rkt
#lang racket
(require racket/runtime-path)
(provide dyn-def)
(define-runtime-path dyn-def "logs/")


Running the test.rkt module it sometimes shows this error, with no
indication of its source:

make-vector: expected argument of type <non-negative exact integer>;
given 693450754.

The number varies, and the error happens usually after 5~10 runs.


I have compiled the latest git version like this

mkdir racket-places
cd racket-places
../src/configure --enable-places --prefix=/usr/racket-5.1.0.2-with-places
make
sudo make install


I end up with version 5.1.0.2--2011-02-05(-/f) [3m].


Any ideas?
-- 
Eduardo Bellani

omnia mutantur, nihil interit.