Call losetup -d properly.

debian/changelog

@@ -1,3 +1,9 @@
+livecd-rootfs (2.830) UNRELEASED; urgency=medium
+
+  * Call losetup -d properly.
+
+ -- Steve Langasek <steve.langasek@ubuntu.com>  Mon, 17 Apr 2023 12:22:06 -0700
+
 livecd-rootfs (2.829) lunar; urgency=medium
 
   [ Loïc Minier ]

live-build/functions

@@ -12,13 +12,13 @@ loop_raw=
 backing_img=
 
 clean_loops() {
-    if [ -n "${backing_img}" ]; then
+    if [ -n "${loop_device}" ]; then
         # If something just finished writing to the device or a
         # partition (e.g. the zerofree in umount_partition) udev might
         # still be processing the device.
         udevadm settle
         sync
-        losetup -v -d "${backing_img}"
+        losetup -v -d "${loop_device}"
         unset backing_img
     fi