def find_reverse_dependencies(spec)
    result = []

    Gem::Specification.each do |sp|
      sp.dependencies.each do |dep|
        dep = Gem::Dependency.new(*dep) unless Gem::Dependency === dep

        if spec.name == dep.name and
           dep.requirement.satisfied_by?(spec.version) then
          result << [sp.full_name, dep]
        end
      end
    end

    result
  end
#
Returns an Array of [specification, dep] that are satisfied by +spec+.