s390x: do not unpack existing initrd, just append LUKS keys to its copy

Signed-off-by: Nikita Dubrovskii <nikita@linux.ibm.com>

src/libostree/s390x-se-luks-gencpio

@@ -4,19 +4,19 @@ set -euo pipefail
 
 old_initrd=$1
 new_initrd=$2
+currdir=$PWD
 
-# Unpacking existing initramdisk
+# Copying existing initramdisk
+cp ${old_initrd} ${new_initrd}
+
+# Appending LUKS root keys and crypttab config to the end of initrd
 workdir=$(mktemp -d -p /tmp se-initramfs-XXXXXX)
 cd ${workdir}
-gzip -cd ${old_initrd} | cpio -imd --quiet
-
-# Adding LUKS root key and crypttab config
 mkdir -p etc/luks
 cp -f /etc/luks/* etc/luks/
 cp -f /etc/crypttab etc/
-
-# Creating new initramdisk image
 find . -mindepth 1 | cpio --quiet -H newc -o | gzip -9 -n >> ${new_initrd}
 
 # Cleanup
+cd ${currdir}
 rm -rf ${workdir}