DebianFiles: annotate 100% with successfull 'mypy'
it's better to start by annotation the base building blocks
I've picked changes from 3 branches.
Please make this test not locale sensitive:
E AssertionError: assert 'Unknown frontend' in 'apt-listchanges\xa0: Interface inconnue\xa0: nonsense\n'
E + where 'apt-listchanges\xa0: Interface inconnue\xa0: nonsense\n' = CaptureResult(out='Enabled debug output\n', err='apt-listchanges\xa0: Interface inconnue\xa0: nonsense\n').err