runruby.rb: don't close other fds

* tool/runruby.rb: rubyspec now requires other FDs not to be
  closed since 7b6ce1fee.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50985 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/runruby.rb

@@ -93,6 +93,7 @@ ENV.update env
 cmd = [ruby]
 cmd.concat(ARGV)
 cmd.unshift(*precommand) unless precommand.empty?
+cmd.push(:close_others => false)
 
 if show
   require 'shellwords'