Elusive coproc bug (Re: coproc tutorial (Re: questions))

["Bart Schaefer" <schaefer@candle.brasslantern.com>]

On Oct 4 I wrote:
} Subject: Re: coproc tutorial (Re: questions)
}
}     coproc tr a-z A-Z
}     exec 5>&p			;: descriptor 5 is now the input of tr
}     exec 6<&p			;: descriptor 6 is now the output of tr
}     coproc sed s/DOG/CAT/ 5>&-
}     exec 7>&p			;: descriptor 7 is now the input of sed
}     exec 8<&p			;: descriptor 8 is now the output of sed
}     coproc exit		;: close p
}     cat <&6 >&7 5>&- 7>&- &	 : tr is now connected to sed
}     exec 6<&- 7>&-		;: close shell copies of descriptors
}     echo dog >&5		;: send tr some input
}     exec 5>&-			;: close 5 so tr will exit
}     cat <&8			;: should print CAT
} 
} [...] this doesn't actually work in 3.0.6, because zsh "leaks" copies of
} descriptors 5 and 7 as descriptors 13 and 14 ("strace" is your friend)

I've now completely failed to duplicate this bug both on the machine where
I first noticed it and on my machine at home, so it must depend on some
other thing that I did earlier within that same shell.  That worries me
a bit, so if any of you happen to feel like experimenting with this (or
have any idea what may be going on), I'd appreciate hearing about it.

Meanwhile, the above appears to work as expected in a freshly-started zsh
of either version series.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com