resolve_for_multiple

# File lib/rubygems/resolver.rb, line 387
  def resolve_for_multiple needed, specs, states, dep, possible # :nodoc:
    # Sort them so that we try the highest versions first.
    possible = possible.sort_by do |s|
      [s.source, s.version, s.platform == Gem::Platform::RUBY ? -1 : 1]
    end

    spec, act = activation_request dep, possible

    # We may need to try all of +possible+, so we setup state to unwind back
    # to current +needed+ and +specs+ so we can try another. This is code is
    # what makes conflict resolution possible.
    states << State.new(needed.dup, specs, dep, spec, possible, [])

    @stats.record_depth states

    explain :states, states.map { |s| s.dep }

    needed = requests spec, act, needed
    specs = Gem::List.prepend specs, act

    return needed, specs
  end