$ git clone -n https://src.fedoraproject.org/rpms/kclock.git /var/lib/mock/f39-build-1641742-40202/root/chroot_tmpdir/scmroot/kclock
Cloning into '/var/lib/mock/f39-build-1641742-40202/root/chroot_tmpdir/scmroot/kclock'...
$ git fetch origin 6a2449882a16e63141cc71931fc54d31eafe07c2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kclock
 * [new ref]         6a2449882a16e63141cc71931fc54d31eafe07c2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6a24498 23.08.2