gem_version_promoter

# File lib/bundler/definition.rb, line 133
    def gem_version_promoter
      @gem_version_promoter ||= begin
        locked_specs =
          if unlocking? && @locked_specs.empty? && !@lockfile_contents.empty?
            # Definition uses an empty set of locked_specs to indicate all gems
            # are unlocked, but GemVersionPromoter needs the locked_specs
            # for conservative comparison.
            Bundler::SpecSet.new(@locked_gems.specs)
          else
            @locked_specs
          end
        GemVersionPromoter.new(locked_specs, @unlock[:gems])
      end
    end