Please try to reproduce bugs which are not obviously Hurd-specific on Debian GNU/Linux and then file them there.
If you find a genuine issue in Debian GNU/Hurd, please file it in our Alioth bug tracker at http://alioth.debian.org/tracker/?atid=411594&group_id=30628&func=browse If you find a bug in the Hurd or GNU Mach themselves, either file a bug against the respective Debian packages, or directly at http://savannah.gnu.org/bugs/?group=hurd