$ git clone -n https://src.fedoraproject.org/rpms/snapshot.git /var/lib/mock/f39-build-1809759-41827/root/chroot_tmpdir/scmroot/snapshot
Cloning into '/var/lib/mock/f39-build-1809759-41827/root/chroot_tmpdir/scmroot/snapshot'...
$ git fetch origin 89eda8854dacd1db6a2f16743dd68f3fa2eb69d9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/snapshot
 * [new ref]         89eda8854dacd1db6a2f16743dd68f3fa2eb69d9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 89eda88 Backport upstream MR !168 to fix portal requests