> You don't need to support a platform. Just call it unsupported and ignore issues if people report them unless they provide a patch themselves.

This thread is an excellent example why ignoring platforms comes at a cost. It will only get worse when are going to introduce platform and architecture specific code for optimizations and features.

> You can view test results any time by going to https://buildd.debian.org/ and searching for "pythonX.Y". So there is actually a CI for release builds.

The site does not list a s390 builder. There is only a s390x builder.