Quoting "anatoly techtonik" <techtonik@gmail.com>:
Does that mean that I need to figure out why tarball was repacked and manually repack it again with the same changes to do new release?
In this case the maintainer (I) was too lazy/sloppy/whatever to document it properly or add a debian/rules target to do the repacking. In this case, the SWF files of bitten were removed, because they are non-free. See debian/changelog.