live-build/auto/config: If EXTRA_ARCHIVES is set in the environment,

dump its value into config/archives/extra-archives.list.chroot and
config/archives/extra-archives.list.binary.  This makes it easier for a
builder to build an image against an additional PPA.

debian/changelog

@@ -1,3 +1,12 @@
+livecd-rootfs (2.212) UNRELEASED; urgency=medium
+
+  * live-build/auto/config: If EXTRA_ARCHIVES is set in the environment,
+    dump its value into config/archives/extra-archives.list.chroot and
+    config/archives/extra-archives.list.binary.  This makes it easier for a
+    builder to build an image against an additional PPA.
+
+ -- Colin Watson <cjwatson@ubuntu.com>  Mon, 19 May 2014 12:12:15 +0100
+
 livecd-rootfs (2.211) utopic; urgency=medium
 
   * Add an ubuntu-desktop-next project for building a desktop flavour

live-build/auto/config

@@ -498,6 +498,13 @@ EOF
 		;;
 esac
 
+if [ "$EXTRA_ARCHIVES" ]; then
+	printf '%s\n' "$EXTRA_ARCHIVES" \
+		> config/archives/extra-archives.list.chroot
+	cp -a config/archives/extra-archives.list.chroot \
+	      config/archives/extra-archives.list.binary
+fi
+
 # cribbed from cdimage, perhaps this should be a small helper script in germinate?
 add_inheritance () {
 	case " $inherit " in