$ git clone -n https://src.fedoraproject.org/rpms/R-RPostgres.git /var/lib/mock/f45-build-5901-345/root/chroot_tmpdir/scmroot/R-RPostgres
Cloning into '/var/lib/mock/f45-build-5901-345/root/chroot_tmpdir/scmroot/R-RPostgres'...
$ git fetch origin 0befc7c5433720bfe879aaa72f3ce81c7bb4cd1c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-RPostgres
 * [new ref]         0befc7c5433720bfe879aaa72f3ce81c7bb4cd1c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0befc7c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild