Fixes: <https://issues.guix.gnu.org/44101>.
* gnu/build/bootloader.scm (write-file-on-device): Pass 'no-fail flag instead
of 'no-create. Use a latin-1 transcoder.
* guix/scripts/system/reconfigure.scm (install-bootloader-program): Add a
"disk-installer" argument and use it as a fallback.
(install-bootloader): Adapt accordingly.
* gnu/tests/reconfigure.scm (run-install-bootloader-test): Ditto.
This commit adjusts the upgrade-services system test to not build anything
when computing the derivation for the system test. I came across this when
looking at issues computing the system test derivations to store in the Guix
Data Service.
* gnu/tests/reconfigure.scm (run-upgrade-services-test): Remove the use of,
and definition for ensure-service-file.