So, I guess we have missed some code in addons manager, which still talks to Mozilla.
I think platform specific details are largely irrelevant here, but anyway:
OS: Mac OS 10.13.3 High Sierra
Commit: https://github.com/MoonchildProductions ... 994d84c963 (latest master)
Below is my .mozconfig.
Found an old article about the exact same issue: http://techdows.com/2015/08/shocking-fi ... d-ons.html