$ git clone -n https://src.fedoraproject.org/rpms/libsigc++20.git /var/lib/mock/f45-build-16968-494/root/chroot_tmpdir/scmroot/libsigc++20
Cloning into '/var/lib/mock/f45-build-16968-494/root/chroot_tmpdir/scmroot/libsigc++20'...
$ git fetch origin d6367840a3cdbe6e74181dbdd743b3462334cba2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libsigc++20
 * [new ref]         d6367840a3cdbe6e74181dbdd743b3462334cba2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d636784 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild