class Gem::DependencyList

def why_not_ok? quick = false
  unsatisfied = Hash.new { |h,k| h[k] = [] }
  each do |spec|
    spec.runtime_dependencies.each do |dep|
      inst = Gem::Specification.any? { |installed_spec|
        dep.name == installed_spec.name and
          dep.requirement.satisfied_by? installed_spec.version
      }
      unless inst or @specs.find { |s| s.satisfies_requirement? dep } then
        unsatisfied[spec.name] << dep
        return unsatisfied if quick
      end
    end
  end
  unsatisfied
end