From the docs on filepath.SkipDir:
> If the function returns SkipDir when invoked on a non-directory file, Walk skips the remaining files in the containing directory
This was causing the bug in #457. Since the file `/etc/hosts` was in the whitelist, when filepath.SkipDir was called the entire etc directory was skipped.
This change only returns filepath.SkipDir on directories.
Priya Wadhwa