trap ': $((brokenpipe+=1))' PIPE

P=${TMPDIR:-/tmp}
cd $P
T=$(mktemp -d sh-test.XXXXXX)
cd $T

brokenpipe=0
mkfifo fifo1 fifo2
{
	{
		exec ${SH} -c 'exec <fifo1; read dummy'
	} 7<&- # fifo2 should be kept open, but not passed to programs
	true
} 7<fifo2 &

exec 4>fifo2
exec 3>fifo1
echo dummy >&4 2>/dev/null
if [ $brokenpipe -eq 1 ]; then
	: ${rc:=0}
fi
echo dummy >&3
wait

rm fifo1 fifo2
rmdir ${P}/${T}
exit ${rc:-3}