One of our builds has randomly started failing on the bundle install stage

This is the build: https://circleci.com/gh/Funzing/funzing-server/10626

it says it’s failing for this reason:

bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 
The git source `git://github.com/arojoal/jquery-multiselect-rails.git` uses the `git` protocol, which transmits data without encryption. Disable this warning with `bundle config git.allow_insecure true`, or switch to the `https` protocol to keep your data secure.
https://github.com/Funzing/debitcredit.git (at master@1885af7) is not yet
checked out. Run `bundle install` first.
The git source `git://github.com/arojoal/jquery-multiselect-rails.git` uses the `git` protocol, which transmits data without encryption. Disable this warning with `bundle config git.allow_insecure true`, or switch to the `https` protocol to keep your data secure.
Fetching https://github.com/Funzing/debitcredit.git
Warning: Permanently added the RSA host key for IP address '192.30.253.113' to the list of known hosts.

Fetching https://github.com/Funzing/state-noitifier.git
Fetching git://github.com/arojoal/jquery-multiselect-rails.git
Fetching gem metadata from https://rubygems.org/.......
Fetching version metadata from https://rubygems.org/..
Fetching dependency metadata from https://rubygems.org/.
Resolving dependencies.....
Your bundle is locked to rest_client (1.7.3), but that version could not be
found in any of the sources listed in your Gemfile. If you haven't changed
sources, that means the author of rest_client (1.7.3) has removed it. You'll
need to update your bundle to a different version of rest_client (1.7.3) that
hasn't been removed in order to install.

bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3  returned exit code 7

Action failed: bundle install

But this error does not make any sense since nothing has change in our gemfile and that author of rest_client didn’t remove that gem verions from rubygems. in fact, here it is: https://rubygems.org/gems/rest-client/versions/1.7.3

should I just upgrade my gem?

Somehow it was fixed on my next merge to that branch.

RESOLVED.