Description of problem:

When having more than one "rescue" entry in the /etc/zipl.conf file, the utility dies after printing "BLS file /boot/loader/entries/<MACHINEID>-0-rescue.conf already exists".

This is due to having the file name "<MACHINEID>-0-rescue.conf" hardcoded, as soon as one "rescue" entry exists.

Typically the tool will die if a system has been cloned and there exists already another "rescue" entry for a different machine id.

Version-Release number of selected component (if applicable):

s390utils-base-2.15.1-5.el8.s390x

How reproducible:

Always

Steps to Reproduce:
1. Create a /etc/zipl.conf from a RHEL7 which contains 2 rescue entries

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
[defaultboot]
defaultauto
prompt=1
timeout=5
default=Red_Hat_Enterprise_Linux_Server_7.9_Rescue_7fef08a17f6a400db03b693a0ef30ba0
target=/boot
[Red_Hat_Enterprise_Linux_Server_7.9_Rescue_7fef08a17f6a400db03b693a0ef30ba0]
image=/boot/vmlinuz-0-rescue-7fef08a17f6a400db03b693a0ef30ba0
parameters="root=/dev/mapper/rootvg-root vmalloc=4096G user_mode=home console=ttyS0 crashkernel=auto rd.lvm.lv=rootvg/root LANG=en_US.UTF-8 ipv6.disable=1 transparent_hugepage=never vmhalt=LOGOFF vmpoff=LOGOFF"
ramdisk=/boot/initramfs-0-rescue-7fef08a17f6a400db03b693a0ef30ba0.img
[3.10.0-1160.25.1.el7.s390x]
image=/boot/vmlinuz-3.10.0-1160.25.1.el7.s390x
parameters="root=/dev/mapper/rootvg-root vmalloc=4096G user_mode=home console=ttyS0 crashkernel=auto rd.lvm.lv=rootvg/root LANG=en_US.UTF-8 ipv6.disable=1 transparent_hugepage=never vmhalt=LOGOFF vmpoff=LOGOFF"
ramdisk=/boot/initramfs-3.10.0-1160.25.1.el7.s390x.img
[linux-0-rescue-fbf2f10617024e97989bccd4d299ec21]
image=/boot/vmlinuz-0-rescue-fbf2f10617024e97989bccd4d299ec21
ramdisk=/boot/initramfs-0-rescue-fbf2f10617024e97989bccd4d299ec21.img
parameters="root=/dev/mapper/rootvg-root vmalloc=4096G user_mode=home console=ttyS0 crashkernel=auto rd.lvm.lv=rootvg/root ipv6.disable=1 transparent_hugepage=never vmhalt=LOGOFF vmpoff=LOGOFF"
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Adjust machine id "7fef08a17f6a400db03b693a0ef30ba0" to the system's one ideally.

2. Execute zipl-switch-to-blscfg after deleting /boot/loader/entries directory

1. rm -fr /boot/loader/entries
2. zipl-switch-to-blscfg

Actual results:

BLS file /boot/loader/entries/7fef08a17f6a400db03b693a0ef30ba0-0-rescue.conf already exists

Expected results:

A Warning that the entry couldn't be created and machine-id differs somehow.

Additional info:

The code responsible to create the file is shown below:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
168 if [ -n "${zipl_to_bls[$key]}" ]; then
169 if [[ $key = "image" && $version_name == true ]]; then
170 if [[ $val = "vmlinuz-" ]]; then
171 version="${val##*/vmlinuz-}"
172 else
173 version="${val##*/}"
174 fi
175 echo "version $version" >> ${OUTPUT}
176 if [[ $version = "rescue" ]]; then
177 FILENAME=${BLS_DIR}/${MACHINE_ID}0-rescue.conf
:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

On line 177 we can see that FILENAME is dependent on machine id, but not actually machine id found in rescue entry extracted from kernel image, here above "/boot/vmlinuz-0-rescue-fbf2f10617024e97989bccd4d299ec21".