Bundler is installed before executing bundle install, in case a Gemfile.lock is present. The specific version defined in the Gemfile.lock under BUNDLED WITH is installed and used to run the bundle install command.
The issues fixed include the error messages printed during build: rbenv: bundle: command not found
and You must use Bundler 2 or greater with this lockfile.
Updated Bitrise Docs URL printed if Apple Developer Portal connection is not set up.