pkg_tar with "include_runfiles = True" includes _main/app.exe in tarfile (exe is included twice)

I have the following pkt_tar in BUILD.bazel

```
pkg_tar(
name = "tarfile",
srcs = [
":openroad",
],
include_runfiles = True,
package_file_name = "openroad.tar",
)
```

The generated tarfile contains the binary "openroad" at root (as expected) plus the binary again at openroad.runfiles/_main/openroad.

The tarfile should only contain the binary at the root level.