fix the condition
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63538 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
fix the condition
nil while the target process is alive.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63538 b2dd03c8-39d4-4d8f-98ff-823fe69b080e