From what I can tell, it looks like Gemstash was used as a reference to build google-cloud-gemserver. There are certainly pattern similarities, but a lot of the codebase has been rewritten. The foundational structure is definitely very similar, but the code within it is different.
Edit >> Adding References (Excuse my formatting.)
gemstash.rb
* https://github.com/bundler/gemstash/blob/master/lib/gemstash...
* https://github.com/GoogleCloudPlatform/google-cloud-gemserve...
version.rb
* https://github.com/bundler/gemstash/blob/master/lib/gemstash...
* https://github.com/GoogleCloudPlatform/google-cloud-gemserve...
setup
* https://github.com/bundler/gemstash/blob/master/bin/setup
* https://github.com/GoogleCloudPlatform/google-cloud-gemserve...
Just a few examples of similarities. The file location is identical as well.