possible memory leak in Nokogiri 1.5.6

mem.rb

#!/usr/bin/env ruby

require 'nokogiri'

def get_memory_usage
  `ps -o rss= -p #{Process.pid}`.to_i
end

HTML_CONTENT = "This is some html<br/>This is some more html<br/>" * 10

def run_nokogiri
  doc = Nokogiri::HTML.parse(HTML_CONTENT)
  doc.css("br").each { |node| node.replace("\n ")}
  doc.text

  nil
end

i = 0
loop do
  run_nokogiri

  i += 1
  if i % 1000 == 0
    GC.start

    puts "iteration #{i}"
    puts "current memory: #{get_memory_usage}"
  end
end