it may stuck with console on readline 5.1 + CentOS 5

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42142 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-07-24

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42143 b2dd03c8-39d4-4d8f-98ff-823fe69b080e