The point that they want to track the versions of gems rubygems.org depends on in a VCS and track the dependency for each version of rubygems.org. You can build

The point that they want to track the versions of gems rubygems.org depends on in a VCS and track the dependency for each version of rubygems.org. You can build a container that includes those, but then you'd have to keep the container in a VCS - that's obviously possible but tangential to the problem.