LGTM.com - false positive: Conflicting values for attributes w.r.t abstractmethod

**Description of the false positive**

LGTM alerted that I have "conflicting values for attributes", but if we check the code, there is no conflict:

* The rightmost superclass has `@abstractmethod` decorator for the method, while
* The leftmost superclass implemented that abstract method

**URL to the alert on the project page on LGTM.com**

https://lgtm.com/projects/g/aio-libs/aiosmtpd/snapshot/f80aed40e36142c228f76ef818901b8f27a2a82e/files/aiosmtpd/controller.py?sort=name&dir=ASC&mode=heatmap#x6e4b5b9c9dfdc9ba:1

https://lgtm.com/projects/g/aio-libs/aiosmtpd/snapshot/f80aed40e36142c228f76ef818901b8f27a2a82e/files/aiosmtpd/controller.py?sort=name&dir=ASC&mode=heatmap#x120237e073ef639d:1

Code links:
* [The @abstractmethod of the rightmost superclass](https://lgtm.com/projects/g/aio-libs/aiosmtpd/snapshot/f80aed40e36142c228f76ef818901b8f27a2a82e/files/aiosmtpd/controller.py?sort=name&dir=ASC&mode=heatmap#L209)
* [The concrete method of the leftmost superclass](https://lgtm.com/projects/g/aio-libs/aiosmtpd/snapshot/f80aed40e36142c228f76ef818901b8f27a2a82e/files/aiosmtpd/controller.py?sort=name&dir=ASC&mode=heatmap#L393)