issue resolved, looks like rsync does not make exact copies. When using tar (not from busybox, the real one) it works. http://maemo.org/pipermail/maemo-dev...er/006113.html
/home/user # dpkg -x ./tar_1.15.1_arm.deb ./toto /home/user # ./toto/bin/tar /bin/sh: ./toto/bin/tar: not found /home/user # ls -l ./toto/bin/tar -rwxrwxr-x 1 1000 1000 194452 Apr 2 2006 ./toto/bin/tar /home/user #