Use the block form of Open3.popen3 to close FDs.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46257 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rake/support/ruby_runner.rb

@@ -18,12 +18,13 @@ module RubyRunner
   def run_ruby(option_list)
     puts "COMMAND: [#{RUBY} #{option_list.join ' '}]" if @verbose
 
-    inn, out, err, wait = Open3.popen3(RUBY, *option_list)
+    Open3.popen3(RUBY, *option_list) {|inn, out, err, wait|
       inn.close
 
       @exit = wait ? wait.value : $?
       @out = out.read
       @err = err.read
+    }
 
     puts "OUTPUT:  [#{@out}]" if @verbose
     puts "ERROR:   [#{@err}]" if @verbose