Re-Exec init after pivot_root

[Ian Oliver]

In article 
<9709bd390703210227id6b0cc5i65f135632201bfc3 at mail.gmail.com>, Alberto 
Donato wrote:
> I agree with Denis. I'm using the same process to update a system
> partition on an embedded system using another one as update system.
> Basically these are the steps:
> 
> mount $UPDATE_PARTITION $UPDATE_DIR
> cd $UPDATE_DIR
> pivot_root . old_root
> chroot . /bin/kill -QUIT 1 &

We have most of this working, but I have a stupid question.

Why is the chroot required on the last line?
Why is the ampersand required?

Thanks!

Ian