$ git clone -n https://src.fedoraproject.org/rpms/fastback.git /var/lib/mock/f45-build-8695-394/root/chroot_tmpdir/scmroot/fastback
Cloning into '/var/lib/mock/f45-build-8695-394/root/chroot_tmpdir/scmroot/fastback'...
$ git fetch origin b46aa2b048c74ba44628c54bba275c50d5f8a2c0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fastback
 * [new ref]         b46aa2b048c74ba44628c54bba275c50d5f8a2c0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b46aa2b Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild