$ git clone -n https://src.fedoraproject.org/rpms/libfastjson.git /var/lib/mock/f45-build-16162-483/root/chroot_tmpdir/scmroot/libfastjson
Cloning into '/var/lib/mock/f45-build-16162-483/root/chroot_tmpdir/scmroot/libfastjson'...
$ git fetch origin ffa31f3f666e050931ba1d7e41d075256723d738:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libfastjson
 * [new ref]         ffa31f3f666e050931ba1d7e41d075256723d738 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ffa31f3 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild