pwhash check_condition unexpected keyword argument {0}

I'm seeing this error on Mac with python version 3.6.5 and pynacl version 1.2.1:

venv3/lib/python3.6/site-packages/nacl/pwhash/argon2id.py:109: in kdf
    ALG)
venv3/lib/python3.6/site-packages/nacl/bindings/crypto_pwhash.py:375: in crypto_pwhash_alg
    raising=exc.TypeError)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cond = False, args = (), kwds = {}, _CHK_UNEXP = 'check_condition() got an unexpected keyword argument {0}', raising = <class 'nacl.exceptions.TypeError'>

    def ensure(cond, *args, **kwds):
        """
        Return if a condition is true, otherwise raise a caller-configurable
        :py:class:`Exception`
        :param bool cond: the condition to be checked
        :param sequence args: the arguments to be passed to the exception's
                              constructor
        The only accepted named parameter is `raising` used to configure the
        exception to be raised if `cond` is not `True`
        """
        _CHK_UNEXP = 'check_condition() got an unexpected keyword argument {0}'

        raising = kwds.pop('raising', AssertionError)
        if kwds:
            raise TypeError(_CHK_UNEXP.format(repr(kwds.popitem()[0])))

        if cond is True:
            return
>       raise raising(*args)
E       nacl.exceptions.TypeError

venv3/lib/python3.6/site-packages/nacl/exceptions.py:68: TypeError

Do you have an idea what this means?

Start by reproducing the traceback with Python 3.6.5 and PyNaCl 1.2.1, then inspect nacl/pwhash/argon2id.py and nacl/bindings/crypto_pwhash.py around the reported calls. Determine why ensure receives an unexpected keyword argument and confirm the affected password-hashing path works without the error.