Wrong fields list when a field is overridden in a subclass

[smarie]

class A(object):
    a = field(default='hello')

class B(A):
    b = field(default='world')

    def a(self):
        pass

    __init__ = make_init()

B(a='h', b='w')

yields TypeError: __init__() got an unexpected keyword argument 'a'