Bug#1073210: systemd-boot-efi: loader.conf default entry incompatibility

[Christoph Ziebuhr]

Package: systemd-boot-efi
X-Debbugs-Cc: chris at codefrickler.de
Version: 252.22-1~deb12u1
Severity: normal
Tags: upstream

We are managing IoT devices as a product, which consists of two root partitions with corresponding
loader/entries/*.conf file on the EFI partition. On each update, a whole image gets written to the currently unused partition
and the default entry in loader/loader.conf gets updated to point to the new loader/entries/*.conf file.

After upgrading our image from debian buster to bookworm, the system booted into the wrong partition.

The issue seems to have been introduced in https://github.com/systemd/systemd/pull/13953.

Previously, in order to point to loader/entries/root1.conf, "default root1" was needed in loader/loader.conf.
Now, it needs to be "default root1.conf". The ".conf" no longer gets stripped when searching for existing entries.

This change is backward incompatible and breaks our update mechanism, which was meant to be stable for long term.