$ git clone -n https://src.fedoraproject.org/rpms/gsl-lite.git /var/lib/mock/f45-build-13250-448/root/chroot_tmpdir/scmroot/gsl-lite
Cloning into '/var/lib/mock/f45-build-13250-448/root/chroot_tmpdir/scmroot/gsl-lite'...
$ git fetch origin bd5b51724d19bbfddf34b52b44f6994c3cd8c89c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gsl-lite
 * [new ref]         bd5b51724d19bbfddf34b52b44f6994c3cd8c89c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bd5b517 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild