REP-855 This is all the stuff for making Deb's and RPM's cleaned up a bit and ready for Servo.

We used to have a dist datastore filter. we removed it and put this check into place. this should have been running on the debs back then. adding it now is safe, because the filter is still gone. and somebody may try to do a jump from that old version to the new. i'd say in a couple of months we should remove the check.