def paths_split(paths, filename)
      paths.each do |path|
        if subpath = split_subpath(path, filename)
          return path, subpath
        end
      end
      nil
    end
def paths_split(paths, filename)
      paths.each do |path|
        if subpath = split_subpath(path, filename)
          return path, subpath
        end
      end
      nil
    end
Internal: Detect root path and base for file in a set of paths.

 paths    - Array of String paths
 filename - String path of file expected to be in one of the paths.

 Returns [String root, String path]