Avoid purging packages for ubuntu-cpc

With the switch to the ubuntu-cloud-minimal seed, we
don't really need to purge anything now. On the contrary,
the purging of packages if not installed, fails with the
exit code of 100.

live-build/auto/build

@@ -369,6 +369,9 @@ EOF
 	# done in chroot hooks.
 	if [ -z "$PASSES" ]; then
 		if [ "${SUBPROJECT:-}" = minimized ]; then
+			# ubuntu-cpc has moved to using ubuntu-cloud-minimal seed
+			# for minimized images, so don't need these purges anymore.
+			if [ "$PROJECT" != ubuntu-cpc ]; then
 				# force removal of initramfs-tools, which we assert is not
 				# required for any minimized images but is still pulled in by
 				# default
@@ -383,7 +386,7 @@ EOF
 				# an initramfs despite the generic dpkg-divert; so remove it
 				# here.
 				rm -f chroot/boot/initrd.img-*
-
+			fi
 			# temporary workaround: don't remove linux-base which
 			# may have no other reverse-depends currently
 			Chroot chroot "env DEBIAN_FRONTEND=noninteractive \