I've checked in Stretch and it is working fine. I've seen that the Debian.mirrors list is generated with the file utils/get_debian_mirrors.py, that is called by pre-build.sh. The bug is still present in LMDE, but the version there is quite old (0.9). I'm closing the bug with a wontfix.
Thank you!
signature.asc
Description: OpenPGP digital signature
