`rtype` of function that returns None is injected into code block

[nineteendo]

Example: https://jsonyx.readthedocs.io/en/latest/api/jsonyx.dump.html

def dump(...) -> None:
    r"""Serialize a Python object to an open JSON file.

    :raises TypeError: for unserializable values
    :raises ValueError: for invalid values

    >>> import jsonyx as json
    >>> json.dump(["foo", {"bar": ("baz", None, 1.0, 2)}])
    ["foo", {"bar": ["baz", null, 1.0, 2]}]
    >>> from io import StringIO
    >>> io = StringIO()
    >>> json.dump(["streaming API"], io)
    >>> io.getvalue()
    '["streaming API"]\n'
    """

[hoodmane]

Buggy docutils strikes again.