- force a BLS config if /boot/loader/entries directory exists (#1755899)

The /usr/lib/kernel/install.d/20-zipl-kernel.install script checks if the
/sbin/new-kernel-pkg script exists to determine whether a BLS config has
to be used or not.

This file should not exist in RHEL8 but it does in some corner cases for
example when doing an in-place upgrade from RHEL7 to RHEL8 since it is
required by the LEAPP tool for the RPM transaction to succeeded.

To cover that, not only check if the /sbin/new-kernel-pkg is not present
but also if the /boot/loader/entries directory exists and use either of
these as a condition to use a BLS configuration.

20-zipl-kernel.install

@@ -74,7 +74,7 @@ case "$COMMAND" in
             fi
         fi
 
-        if [[ ! -f /sbin/new-kernel-pkg ]]; then
+        if [[ ! -f /sbin/new-kernel-pkg || -d "$BLS_DIR" ]]; then
             declare -a BOOT_OPTIONS
             if [[ -f /etc/kernel/cmdline ]]; then
                 read -r -d '' -a BOOT_OPTIONS < /etc/kernel/cmdline