rhel: work around RHEL-9 BLS issues

Similar to the CentOS-9-Stream fix [1] this change renames the default
BLS entry to match the current machine-id so that grub2-mkconfig calls
will refresh the kernel options.

However there is an additional issue with the rhel-9 base image. It is
unique in having a dedicated boot partition, so the path to the kernel
and initramfs don't include /boot. This results in an unbootable image
when /boot is a directory of the root partition.

These paths do not get corrected by calling grub2-mkconfig, so this
change performs a sed on the paths to fix them for a root partition
/boot.

[1] I327f5e7a95e47905c01138c8c4483f3f03e8efff
Change-Id: I37a1d310e1854f4a49725e355d484e456ea4fc7a

diskimage_builder/elements/rhel/pre-install.d/03-reset-bls-entries

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -eu
+set -o pipefail
+
+if [[ ! '9' =~ ${DIB_RELEASE} ]]; then
+    exit 0
+fi
+
+# This is a workaround for the grub issue reported upstream with
+#  https://bugzilla.redhat.com/show_bug.cgi?id=2032680
+
+# This renames the BLS entries from the upstream .qcow2 image in
+# /boot/loader/entries with the current machine-id. This means that in the
+# bootloader setup, grub2-mkconfig will update config options as required.
+
+pushd /boot/loader/entries
+
+machine_id=$(</etc/machine-id)
+
+for entry in *.conf; do
+    new_entry=$(echo $entry | sed "s/^[a-f0-9]*/$machine_id/")
+    echo "renaming $entry to $new_entry for new machine-id"
+    if [[ $entry != $new_entry ]]; then
+        mv $entry $new_entry
+    fi
+
+    # RHEL-9 is unique in having a separate /boot partition, fix the paths to assume
+    # /boot will be in the root partition.
+    sed -i "s| /vmlinuz| /boot/vmlinuz|" $new_entry
+    sed -i "s| /initramfs| /boot/initramfs|" $new_entry
+done
+popd
+
+echo "--- Show kernels ---"
+grubby --info=ALL