-Do not delete debian/files. When do you want to use this? Anytime you have a
-debian/rules that has 2 binary targets that build different .deb packages;
-for example, one target is binary-arch, and the other is binary-indep, or
-one target builds the shared library, and the other the -dev package. If you
-didn't use -k in these cases, then debian/files would be deleted in the
-middle, and your changes file will only contain the last binary package that
-was built.