$ git clone -n https://src.fedoraproject.org/rpms/showcert.git /var/lib/mock/f45-build-35958-700/root/chroot_tmpdir/scmroot/showcert
Cloning into '/var/lib/mock/f45-build-35958-700/root/chroot_tmpdir/scmroot/showcert'...
$ git fetch origin 4a9f6eefa62cd199808f713a490433ade3a8db06:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/showcert
 * [new ref]         4a9f6eefa62cd199808f713a490433ade3a8db06 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4a9f6ee Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild