py3-qt5 no longer includes QtWebengine support
$ python3 >>> import PyQt5.QtWebengineWidgets Traceback (most recent call last): File "", line 1, in ModuleNotFoundError: No module named 'PyQt5.QtWebengineWidgets'
I spent a few minutes looking into this but the problem wasn’t immediately apparent.
(from redmine: issue id 10035, created on 2019-02-25, closed on 2019-06-19)