the debian package shows a lot of drush backend garbage

this is how the hostmaster-install command gets called in the debian package:

            su -s /bin/sh aegir -c "cd $VARLIB && drush hostmaster-install $FLAGS --backend $site_uri | drush backend-parse" <<EOF

But unfortunately, that spews out a lot of stuff like:

DRUSH_BACKEND:{"type":"bootstrap","message":"Found command: hosting-setup (commandfile=hosting)","timestamp":1369341069.9458,"memory":10989188,"error":null,"packet":"log"}

It seems that drush backend-parse (part of provision) doesn't work anymore.