LGTM.com - false positive

**Description of the false positive**

This function is calling super. It's using python2-compatible syntax in a python3-only project, but the call to init still works.

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

https://lgtm.com/projects/g/mirumee/django-payments/rev/pr-cf8a1ae2dfa932f0fcc02f031698bbd57324c063

Relevant
https://github.com/mirumee/django-payments/pull/223#issuecomment-670149501

Can't do the inline instructions:

1. Open the project on LGTM.com.
For example, https://lgtm.com/projects/g/pallets/click/.
2. Switch to the `Alerts` tab. For example, https://lgtm.com/projects/g/pallets/click/alerts/.
3. Scroll to the alert that you would like to report. <-- doesn't show up here.
4. Click on the right most icon `View this alert within the complete file`.
5. A new browser tab opens. Copy and paste the page URL here.
For example, https://lgtm.com/projects/g/pallets/click/snapshot/719fb7d8322b0767cdd1e5903ba3eb3233ba8dd5/files/click/_winconsole.py#xa08d213ab3289f87:1.

I've no idea how to change the branch on the UI, there's on clean way of doing it.