Looks like a bug from the backport team. They should have specified the dependency on sauerbraten-data to be >=0.0.20080620-1~hardy1 instead of >= 0.0.20080620-1 (which fails since 0.0.20080620-1~hardy1 << 0.0.20080620-1 so the sauerbraten from backports is not installable).
Looks like a bug from the backport team. They should have specified the dependency on sauerbraten-data to be >=0.0.20080620- 1~hardy1 instead of >= 0.0.20080620-1 (which fails since 0.0.20080620- 1~hardy1 << 0.0.20080620-1 so the sauerbraten from backports is not installable).