Ruby `%setup` unpacks `.gem` file (`SOURCE0`), and also generates `.gemspec`
file (from the `.gem` file) which is needed for gem build:
https://src.fedoraproject.org/rpms/rubygem-rails/blob/rawhide/f/rubygem-rails.spec#_37
It's generated in the same folder as the unpacked source (to avoid name
Well, it's only a binding, not having anything compiled.
Should this work for different-arch builders as well?
```
DEBUG util.py:621: Error:
DEBUG util.py:621: Problem: package ruby-libs-2.7.1-134.fc33.s390x requires
libffi.so.6()(64bit), but none of the providers can be installed
DEBUG
