Fix counting of images at build time

Closes: #1063858
(cherry picked from commit 64c59791cf)

debian/changelog

@@ -2,12 +2,12 @@ debian-cd (3.1.35+deb11u1) UNRELEASED; urgency=medium
 
   [ Steve McIntyre ]
   Backports from master for bullseye builds:
-
   * Use $CODENAME/updates for security pre-bullseye, or
     $CODENAME-security for bullseye onwards.
   * Tweak grub boot menu highlight graphics to work again - switch
     from greyscale to colour, as newer grub has removed greyscale PNG
     support.. Closes: #1013079, #1013432.
+  * Fix counting of images at build time. Closes: #1063858
 
  -- Steve McIntyre <93sam@debian.org>  Mon, 26 Jul 2021 01:02:03 +0100
 

tools/make_image

@@ -19,13 +19,11 @@ NUM_ARCHES=`echo $ARCHES | wc -w`
 
 if [ "$CD"x = ""x ] ; then
     echo "Generating the $ARCHES iso/jigdo images ..."
-    FILES=$DIR/*.volid
 else
     echo "Generating $ARCHES iso/jigdo image number $CD ..."
-    FILES=$DIR/$CD.volid
 fi
 
-NUM_CDS=`ls -1 $FILES | wc -l`
+NUM_CDS=$(ls -1 $DIR/*.volid | wc -l)
 
 last_minute_update () {
     echo "  Last-minute updates:"