$ git clone -n https://src.fedoraproject.org/rpms/guile-gnutls.git /var/lib/mock/f45-build-13238-447/root/chroot_tmpdir/scmroot/guile-gnutls
Cloning into '/var/lib/mock/f45-build-13238-447/root/chroot_tmpdir/scmroot/guile-gnutls'...
$ git fetch origin 91dba79547ee87edf8b1d9bd5915d329ca6ab00a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/guile-gnutls
 * [new ref]         91dba79547ee87edf8b1d9bd5915d329ca6ab00a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 91dba79 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild