def filter_nonexistent(modified_files)
      modified_files.select do |file|
        File.exist?(file) || Overcommit::Utils.broken_symlink?(file)
      end
    end
def filter_nonexistent(modified_files)
      modified_files.select do |file|
        File.exist?(file) || Overcommit::Utils.broken_symlink?(file)
      end
    end
Filter out non-existent files (unless it's a broken symlink, in which case
 it's a file that points to a non-existent file). This could happen if a
 file was renamed as part of an amendment, leading to the old file no
 longer existing.