attempt_to_activate

# File lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb, line 668
      def attempt_to_activate
        debug(depth) { 'Attempting to activate ' + possibility.to_s }
        existing_vertex = activated.vertex_named(name)
        if existing_vertex.payload
          debug(depth) { "Found existing spec (#{existing_vertex.payload})" }
          attempt_to_filter_existing_spec(existing_vertex)
        else
          latest = possibility.latest_version
          # use reject!(!satisfied) for 1.8.7 compatibility
          possibility.possibilities.reject! do |possibility|
            !requirement_satisfied_by?(requirement, activated, possibility)
          end
          if possibility.latest_version.nil?
            # ensure there's a possibility for better error messages
            possibility.possibilities << latest if latest
            create_conflict
            unwind_for_conflict
          else
            activate_new_spec
          end
        end
      end