$ git clone -n https://src.fedoraproject.org/rpms/snapshot.git /var/lib/mock/f40-build-2270585-54828/root/chroot_tmpdir/scmroot/snapshot
Cloning into '/var/lib/mock/f40-build-2270585-54828/root/chroot_tmpdir/scmroot/snapshot'...
$ git fetch origin 5dee2051b9e81cd906326a83b380555d2a7f8f82:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/snapshot
 * [new ref]         5dee2051b9e81cd906326a83b380555d2a7f8f82 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5dee205 Update to 45.2