Build fails, cannot mount /proc while inside chroot

["Will Murnane" <will.murnane@gmail.com>]

Hello,
  I just tried to build debian live again, and got the following
message as it failed:
I: Extracting tzdata...
I: Extracting util-linux...
I: Extracting zlib1g...
W: Failure trying to run: chroot /live/chroot mount -t proc proc /proc
Running this command manually yields:
root@debian:/live# chroot /live/chroot mount -t proc proc /proc
mount: only root can do that
and chrooting into a shell shows that it can't determine the user id:
I have no name!@debian:/#
However, a quick test seems to show that mounting /proc under the
chroot directory works:
root@debian:/live# mount -t proc proc /live/chroot/proc/
root@debian:/live# mount
...
proc on /live/chroot/proc type proc (rw)
Now, I have /live mounted over NFS; could this be causing the problem?
 I don't see why it would, but I thought I'd mention it in case it is
relevant.

In any case, mounting /live/chroot/proc as shown above seems to work,
but running the build again after that fails.  Any suggestions what I
might do to fix this?

Thanks!
Will