Background: I am attempting to modernise a legacy Rails app. I am not a full-time developer, nor am I the app’s maintainer. All CI tests currently pass with 79% of coverage.

In the Gemfile, rails is pointed to the 3-2-stable branch of a fork of the main Rails repo. On that branch, the RAILS_VERSION file has the content 3.2.22.5.

Now, I logically assumed that removing the Git reference and pinning to 3.2.22.5 would be fine, however when I update the Gemfile and run bundle install I get a heap of dependency errors, which doesn’t make sense – I’m just changing the source, not the version of the gem.

Can I force Bundler to just update the source? Should I manually hack the Gemfile.lock to reflect this?