timeout.rb: defer creating custom exception
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44517 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
timeout.rb: defer creating custom exception
no instance is needed to be caught, so defer creating new instance
until it is raised. [ruby-core:59511] [Bug #9354]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44517 b2dd03c8-39d4-4d8f-98ff-823fe69b080e