Or, more precisely, it returns less than the requested number of
characters because characters are counted before translating newlines:

>>> f = io.StringIO("a\r\nb\r\n", newline=None)
>>> f.read(3)
'a\n'

TextIOWrapper gets it right:

>>> g = io.TextIOWrapper(io.BytesIO(b"a\r\nb\r\n"), newline=None)
>>> g.read(3)
'a\nb'