live build --architectures not set by /usr/share/livecd-rootfs/live-build/auto/config

The host is amd64 and the target is i386.

After Colin Watson post on <email address hidden>
  Once only:
    $ mkdir -p auto
    $ ln -sf /usr/share/livecd-rootfs/live-build/auto/* auto/

  Each time:
    $ export PROJECT=xubuntu SUITE=oneiric ARCH=i386 MIRROR=http://fr.archive.ubuntu.com/ubuntu/
    $ sudo lb clean
    $ lb config
    $ sudo lb build
the build is made of amd64 packages.

Here is a patch working fine:

--- /usr/share/livecd-rootfs/live-build/auto/config 2011-10-07 18:26:19.000000000 +0200
+++ /media/oczV3-14G-live-build/oneiric-CW/auto/config 2011-11-22 12:00:29.679688782 +0100
@@ -240,6 +240,7 @@
 lb config noauto \
     --mode ubuntu \
     --distribution "$SUITE" \
+ --architectures "$ARCH" \
     --bootstrap-keyring ubuntu-keyring \
     --binary-images "$BINARY_IMAGES" \
     --memtest "$MEMTEST" \