Get live-build to divert update-initramfs while building the chroot.

This should cut a few minutes off builds, particularly on slow
architectures.

debian/changelog

@@ -1,7 +1,13 @@
-livecd-rootfs (2.49) UNRELEASE; urgency=low
+livecd-rootfs (2.49) UNRELEASED; urgency=low
 
+  [ Adam Conrad ]
   * Update maintainer to Ubuntu Developers, LaMont doesn't upload much.
 
+  [ Colin Watson ]
+  * Get live-build to divert update-initramfs while building the chroot.
+    This should cut a few minutes off builds, particularly on slow
+    architectures.
+
  -- Adam Conrad <adconrad@ubuntu.com>  Thu, 12 Jan 2012 07:27:16 -0700
 
 livecd-rootfs (2.48) precise; urgency=low

live-build/auto/build

@@ -26,6 +26,27 @@ Expire-Date: 0
 	fi
 
 	lb bootstrap "$@"
+
+	Chroot chroot "dpkg-divert --quiet --add \
+		--divert /usr/sbin/update-initramfs.REAL --rename \
+		/usr/sbin/update-initramfs"
+	cat > chroot/usr/sbin/update-initramfs <<'EOF'
+#! /bin/sh
+if [ $# != 1 ] || [ "$1" != -u ]; then
+	exec update-initramfs.REAL "$@"
+fi
+echo "update-initramfs: diverted by livecd-rootfs (will be called later)" >&2
+exit 0
+EOF
+	chmod +x chroot/usr/sbin/update-initramfs
+
+	cat > config/chroot_local-hooks/zz-undivert-update-initramfs.sh <<'EOF'
+#! /bin/sh
+rm -f /usr/sbin/update-initramfs
+dpkg-divert --quiet --remove --rename /usr/sbin/update-initramfs
+EOF
+	chmod +x config/chroot_local-hooks/zz-undivert-update-initramfs.sh
+
 	lb chroot "$@"
 
 	if [ -d chroot/var/lib/preinstalled-pool ]; then