Filter out registry keys to operate on files.

def _RemoveRegistryKeys(self, metadata_value_pairs):
    """Filter out registry keys to operate on files."""
    filtered_pairs = []
    for metadata, stat_entry in metadata_value_pairs:
      # Ignore registry keys.
      if stat_entry.pathspec.pathtype != rdf_paths.PathSpec.PathType.REGISTRY:
        filtered_pairs.append((metadata, stat_entry))

    return filtered_pairs