Fix kdumpst-load.sh.in with btrfs subvolumes

kdumpst-load.sh.in

@@ -200,7 +200,7 @@ KDUMP_CMDLINE="${KDUMP_CMDLINE} ${KDUMP_APPEND_CMDLINE}"
 #  information. If it fails, then attempt prepending /boot into that (faced
 #  both situations in the field so far).
 VMLINUX="$(grep -o 'BOOT_IMAGE=[^ ]*' /proc/cmdline)"
-VMLINUX="${VMLINUX#*BOOT_IMAGE=}"
+VMLINUX="${VMLINUX#*BOOT_IMAGE=${GRUB_BOOT_IMAGE_PREFIX}}"
 if [ ! -s "${VMLINUX}" ]; then
 	VMLINUX="/boot/${VMLINUX}"
 	if [ ! -s "${VMLINUX}" ]; then
@@ -227,3 +227,7 @@ if ! kexec -s -p "${VMLINUX}" --initrd "${INITRD_FNAME}" --append="${KDUMP_CMDLI
 	exit 1
 fi
 logger "kdumpst: panic kexec loaded successfully"
+
+# Local Variables:
+# indent-tabs-mode: t
+# End: