Bug#1053642: systemd: kernel installation failure due to missing python3 dependency (used by 60-ukify.install)

[Carsten Andrich]

Package: systemd
Version: 254.5-1
Severity: important
X-Debbugs-Cc: carsten at andrich.name

Dear Maintainer,

/usr/lib/kernel/install.d/60-ukify.install requires python3 to run, however
the systemd package currently does not depend on python3.

On minimal systems without python3 this will lead to kernel installation
failure with the following messages:

> Unpacking linux-image-amd64 (6.5.3-1) ...
> Setting up linux-image-amd64 /6.5.3-1) ...
> /etc/kernel/postinst.d/initramfs-tools:
> update-initramfs: Generating /boot/initrd.img-6.5.0-1-amd64
> Updating kernel version 6.5.0-1-amd64 in systemd-boot...
> /usr/bin/env/: 'python3': No such file or directory
> /usr/lib/kernel/install-d/60-ukify.install failed with exit status 127.
> /etc/kernel/postinst.d/zz-systemd-boot:
> Installing kernel version 6.5.0-1-amd64 in systemd-boot...
> /usr/bin/env/: 'python3': No such file or directory
> /usr/lib/kernel/install-d/60-ukify.install failed with exit status 127.

Installing python3 prior to installing a kernel image will fix the issue.
python3-minimal is insufficient, as it does not include the shlex module
imported by 60-ukify.install.

Promoting python3 from Suggests: to Depends: should fix the issue.

Best regards,
Carsten