Calling `config_parser.read` with `'test'` is equivalent to:

    config_parser.read(['test'])

while calling `config_parser.read` with `b'test'` is treated as:

    config_parser.read([116, 101, 115, 116])

which means python will try to open the file descriptors 101, 115 and 116.

I don't know if byte path should be supported, but this is probably not the expected behavior.

The method code: https://github.com/python/cpython/blob/master/Lib/configparser.py#L678-L702