$ git clone -n https://src.fedoraproject.org/rpms/libsigc++.git /var/lib/mock/f39-build-1511536-35542/root/chroot_tmpdir/scmroot/libsigc++
Cloning into '/var/lib/mock/f39-build-1511536-35542/root/chroot_tmpdir/scmroot/libsigc++'...
$ git fetch origin 85ca5ebddd5273cda3a1260fc16e876d9e7be562:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libsigc++
 * [new ref]         85ca5ebddd5273cda3a1260fc16e876d9e7be562 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 85ca5eb Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild