Attempt to restrict task installation to the native architecture.

debian/changelog

@@ -6,6 +6,7 @@ livecd-rootfs (2.76) UNRELEASED; urgency=low
     - Fix installation of ubuntu-server fstab removal hook.
     - Pass --architectures to 'lb config', to make it easier to build images
       for a different architecture.
+    - Attempt to restrict task installation to the native architecture.
 
  -- Colin Watson <cjwatson@ubuntu.com>  Thu, 23 Aug 2012 09:43:38 +0100
 

live-build/auto/config

@@ -39,8 +39,26 @@ add_task ()
 	shift
 	local task
 
+	# The removal of direct task installation support from live-build
+	# poses some problems.  If the chroot has multiarch configured - for
+	# example, if we're building for amd64 - then dumpavail will show
+	# foreign-architecture packages which will have their own Task
+	# lines, but which we don't want to install.  (Compare
+	# PackageContainerInterface::FromTask in apt, which restricts task
+	# expansion to the native architecture.)  We therefore restrict our
+	# search to stanzas with Architecture: $ARCH or all.
+	#
+	# However, even this may not be accurate enough.  At the moment I
+	# have no idea what happens if an Architecture: all package has
+	# different Task fields on different architectures.  This is
+	# probably a lurking timebomb that we need to fix.  In the meantime,
+	# the Architecture restriction at least saves us from abject
+	# failure.
+
 	for task; do
-		echo "!chroot chroot apt-cache dumpavail | grep-dctrl -nsPackage -wFTask $task" >> "config/package-lists/livecd-rootfs.list.chroot_$pass"
+		# We need a ridiculous number of backslashes to protect
+		# parentheses from eval.
+		echo "!chroot chroot apt-cache dumpavail | grep-dctrl -nsPackage \\\\\\( -XFArchitecture $ARCH -o -XFArchitecture all \\\\\\) -a -wFTask $task" >> "config/package-lists/livecd-rootfs.list.chroot_$pass"
 	done
 }