$ git clone -n https://src.fedoraproject.org/rpms/bcm283x-firmware.git /var/lib/mock/f38-build-723139-99022/root/chroot_tmpdir/scmroot/bcm283x-firmware
Cloning into '/var/lib/mock/f38-build-723139-99022/root/chroot_tmpdir/scmroot/bcm283x-firmware'...
$ git fetch origin 489ba9a1607d29ed171540a675a43e71aa0d1f37:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/bcm283x-firmware
 * [new ref]         489ba9a1607d29ed171540a675a43e71aa0d1f37 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 489ba9a Update config.txt for single U-Boot binary