Read loop lossage

[sawyl]

The following works under genuine AT&T Korn shell, but fails under pdksh:

v=0
echo 1 | while read p
do
v=1
done
echo $v

I'd attribute this to the usual ksh lossage if wasn't for the fact that bash does the same thing. Could it be that it's AT&T in the wrong and pdksh in the right? That'd be a first.