Dup'd IO instances should always be set to close-on-exec.
Dup'd IO instances should always be set to close-on-exec.

eregon/rubyspec,ruby/rubyspec,nobu/rubyspec,eregon/rubyspec,ruby/spec,nobu/rubyspec,ruby/spec,ruby/spec,eregon/rubyspec,ruby/rubyspec,nobu/rubyspec