$ git clone -n https://src.fedoraproject.org/rpms/tracker.git /var/lib/mock/f40-build-2043661-48643/root/chroot_tmpdir/scmroot/tracker
Cloning into '/var/lib/mock/f40-build-2043661-48643/root/chroot_tmpdir/scmroot/tracker'...
$ git fetch origin a1959a7838cd381f0e32609ea334d849e3d8b949:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tracker
 * [new ref]         a1959a7838cd381f0e32609ea334d849e3d8b949 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a1959a7 Update to 3.6.0