I would say that anytime a problem with maxmind causes a rebuild to fail, it’s a bug. I’m pretty sure that it’s always been possible for issues with Maxmind to cause a build to fail.
So I don’t know whether it’s the same bug, or multiple bugs.
I think the solution could be as simple as adding a rescue (somewhere in discourse/lib/discourse_ip_info.rb at 3d49df2953fd14ae75eeab7621ad687f1b06f504 · pfaffman/discourse · GitHub) to allow life to go on without Maxmind, regardless of whether a key, valid or invalid, was provided.