[1009262] upgrades: Update blocked by incorrect battery status

FreedomBox 22.8~bpo11+1 on ROCKPro64, using arm64 bullseye image flashed to eMMC.

I am running on AC wall outlet power, and there is no battery that I know of.

==> unattended-upgrades.log
2022-04-07 10:45:28,535 WARNING System is on battery power, stopping
2022-04-07 10:47:55,408 WARNING System is on battery power, stopping
2022-04-07 11:04:47,539 WARNING System is on battery power, stopping

I manually upgraded all packages, and rebooted. I still get the warning.