$ git clone -n https://src.fedoraproject.org/rpms/golang-modernc-opt.git /var/lib/mock/f45-build-12734-443/root/chroot_tmpdir/scmroot/golang-modernc-opt
Cloning into '/var/lib/mock/f45-build-12734-443/root/chroot_tmpdir/scmroot/golang-modernc-opt'...
$ git fetch origin 3e39643ad46493aae64d2e65ee74723925be92b6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-modernc-opt
 * [new ref]         3e39643ad46493aae64d2e65ee74723925be92b6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3e39643 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild