prune_gem_cache

# File lib/bundler/runtime.rb, line 225
    def prune_gem_cache(resolve, cache_path)
      cached = Dir["#{cache_path}/*.gem"]

      cached = cached.delete_if do |path|
        spec = Bundler.rubygems.spec_from_gem path

        resolve.any? do |s|
          s.name == spec.name && s.version == spec.version && !s.source.is_a?(Bundler::Source::Git)
        end
      end

      if cached.any?
        Bundler.ui.info "Removing outdated .gem files from #{Bundler.settings.app_cache_path}"

        cached.each do |path|
          Bundler.ui.info "  * #{File.basename(path)}"
          File.delete(path)
        end
      end
    end