$ git clone -n https://src.fedoraproject.org/rpms/root.git /var/lib/mock/f43-build-side-114791-61027656-6587897/root/chroot_tmpdir/scmroot/root
Cloning into '/var/lib/mock/f43-build-side-114791-61027656-6587897/root/chroot_tmpdir/scmroot/root'...
$ git fetch origin 3a74b8b61031092540cb0b4280d4e1099de2d010:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/root
 * [new ref]         3a74b8b61031092540cb0b4280d4e1099de2d010 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a74b8b Update to 6.36.02