trap problem

[Thomas Ziehmer <ziehmer@rhrk.uni-kl.de>]

Hallo, 
with zsh 3.1.5 (the only tested version) on SGI and HP, but not on Linux, AIX 
and Solaris (there it works correct), the following script produces a wrong
output:

#!/usr/local/bin/zsh

function foo { \
echo step 1
ps
echo step 2
{ echo abcdef ; ps ; } | cat -
echo step 3
}

trap " foo ; exit " INT QUIT TERM HUP

{ time sleep 30 </dev/null ; } 2>/dev/null


ziehmer@o2000 [ziehmer]> t < t
^C
step 1
PID TTY     TIME CMD
21263 ttyq27  0:00 zsh-3.1.5 
23753 ttyq27  0:00 ps 
24969 ttyq27  0:00 t 
step 2
abcdef
step 3

The output of the second ps-command is not shown.
Why?

Regards
Thomas Ziehmer