add timeout to test_do_reply

http://fb64b.rubyci.org/~chkbuild/ruby-trunk/log/20140115T073301Z.log.html.gz

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44616 b2dd03c8-39d4-4d8f-98ff-823fe69b080e