As of #443, all of the rules_pkg files are now in a WORKSPACE relative to the
root of the repository. These are now shared with the `deb_packages/` and
`examples/` subdirectories, which contain their own WORKSPACE files. This
confuses Bazel and prevents us from testing `//...`.
This changes allows us to build/test `//...` by adding those directories to a
.bazelignore file at the root of the repository.
Most people working on rules_pkg aren't going to be touching these, and if they
are, they need to be in those WORKSPACEs anyway, so there should be no harm in
this.