- skip BOOT_IMAGE param when copying the cmdline to BLS snippets

The bootloaders add a BOOT_IMAGE parameter that is present in the kernel
command line exposed via the /proc/cmdline virtual file. If this param
is added to the kernel cmdline in the BLS snippet, it will be duplicated.

Resolves: #1782321

20-zipl-kernel.install

@@ -83,7 +83,7 @@ case "$COMMAND" in
             if ! [[ ${BOOT_OPTIONS[*]} ]]; then
                 read -r -d '' -a line < /proc/cmdline
                 for i in "${line[@]}"; do
-                    [[ "${i#initrd=*}" != "$i" ]] && continue
+                    [[ "${i#initrd=*}" != "$i" || "${i#BOOT_IMAGE=*}" != "$i" ]] && continue
                     BOOT_OPTIONS+=("$i")
                 done
             fi