Fix install_firmwares_initrd to not fail when the firmware is not found.

debian/changelog

@@ -13,6 +13,7 @@ debian-cd (3.1.36) UNRELEASED; urgency=medium
   [ Raphaël Hertzog ]
   * Add cryptsetup-initramfs to tools/generate_di+k_list as cryptsetup 2.4.0
     dropped the recommends on the package and it's needed by d-i.
+  * Fix install_firmwares_initrd to not fail when the firmware is not found.
 
   [ Wolfgang Schweer ]
   * data/bookworm: Use Debian Edu 12 installer logo and syslinux splash image

tools/boot/bookworm/common.sh

@@ -228,7 +228,7 @@ install_firmwares_initrd () {
     regex="$2"
     if [ "$FORCE_FIRMWARE"x = "1"x ]; then
         FILES=`$BASEDIR/tools/catz ${MIRROR}/dists/${DI_DIST}/*/binary-${ARCH}/Packages.gz | \
-            grep-dctrl -Pe "$regex" -sFilename -n`
+            grep-dctrl -Pe "$regex" -sFilename -n || true`
         if [ -n "${FILES}" ]; then
             echo "    Adding firmwares from" ${FILES}
 
@@ -243,6 +243,8 @@ install_firmwares_initrd () {
             (cd ${FWDIR} ; find lib/firmware | cpio -oA -H newc -F $initrd)
             gzip -9 $initrd
             rm -fr $FWDIR
+	else
+	    echo "    WARNING: Could not find firmware package(s) matching $regex"
         fi
     fi
 }