PyCharm Type-Hinting：__ metaclass__ bug？

Question

class MetaProp(type):
    @property
    def value1(cls):
        """
        :rtype: str
        """
        return "A String"

class ClassProp(object):
    __metaclass__ = MetaProp

    @property
    def value2(self):
        """
        :rtype: str
        """
        return "A String"


instance = ClassProp()

assert isinstance(ClassProp.value1, basestring)
assert isinstance(instance.value2, basestring)
assert ClassProp.value1 == instance.value2

def some_method(val):
    """
    :type val: str
    """
    print val

some_method(instance.value2)
some_method(ClassProp.value1)

PyCharm在最后一行给我一个警告，因为＆＃34; value1＆＃34;应该是属性而不是字符串：

代码有效......这是PyCharm中的一个错误，还是我错过了什么？