lb_chroot_layered: fix quoting when searching for trusted.overlay.opaque

debian/changelog

@@ -1,3 +1,10 @@
+livecd-rootfs (2.732) UNRELEASED; urgency=medium
+
+  * lb_chroot_layered: fix quoting when searching for
+    trusted.overlay.opaque
+
+ -- Michael Hudson-Doyle <michael.hudson@ubuntu.com>  Fri, 30 Jul 2021 11:56:01 +1200
+
 livecd-rootfs (2.731) impish; urgency=medium
 
   [ Jason C. McDonald ]

live-build/lb_chroot_layered

@@ -130,7 +130,7 @@ reduce_pass_size () {
 		if ! diff --brief --no-dereference "$pass_dir/$f" "$parent_pass_dir/$f" >/dev/null; then
 			continue
 		fi
-		p=$(dirname $f)
+		p="$(dirname "$f")"
 		while [ "$p" != . ]; do
 			# As explained in the overlayfs documentation
 			# https://www.kernel.org/doc/html/latest/filesystems/overlayfs.html#whiteouts-and-opaque-directories
@@ -147,7 +147,7 @@ reduce_pass_size () {
 				Echo_message "reduce_pass_size: '%s' would be removed from overlay but for trusted.overlay.opaque on '%s'" "$f" "$p"
 				continue 2
 			fi
-			p=$(dirname $p)
+			p="$(dirname "$p")"
 		done
 		# Files are strictly identical between the 2 passes (only mod or access times differs). No need for unused delta.
 		Echo_message "reduce_pass_size: '%s' is strictly identical between %s and %s. Removing." "$f" "$pass" "$parent"