Since, 4ddc78818e systemd-boot-builder
is broken in two ways:
* if no systemd-boot is currently installed *and* the NIXOS_INSTALL_BOOTLOADER
env variable is not set, it will try to run "bootctl update", which will fail
* if the currently installed systemd-boot version is newer than the version
we're about to install, it will also try to run "bootctl update", which will fail
This patch changes the behaviour,
* for the first case to still fail, but not even bother to try running
"bootctl update" and instead erroring out with an exception
* for the second case to leave the newer version in place, restoring
the pre - 4ddc78818e behaviour
To do the proper version check a new "should_update" helper function was introduced,
mimicing the compare_product C function from bootctl. If the following systemd
issue gets resolved, we would have a nice way to get rid of this function:
> https://github.com/systemd/systemd/issues/23450
This change allows to again switch to a different NixOS configuration which contains
an older systemd-boot.
Co-authored-by: Martin Weinelt <mweinelt@users.noreply.github.com>
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