`Failed to load resource: the server responded with a status of 503 (Service Unavailable)`
Gemfly does a simple thing compared to bundle update. The purpose is to replace the versions of your gems in your Gemfile with the latest one. It also adds version if it doesn't have one.
If you have this gem: gem 'rails', '~> 3.2.12'
It will become: gem 'rails', '~> 4.2.3'
If you have: gem 'rails'
It will become: gem 'rails', '~> 4.2.3'
It's recommended to put versions in your Gemfile specially if you're updating to a major version.
I'm happy to merge pull requests as this tool is not just for me but for everyone.