def _ensure_unix_line_endings(path):
    """Replace windows line endings with Unix.  Return path to modified file."""
    out_path = path + '_unix'
    with open(path) as inputfile:
        with open(out_path, 'w') as outputfile:
            for line in inputfile:
                outputfile.write(line.replace('\r\n', '\n'))
    return out_path
