$ git clone -n https://src.fedoraproject.org/rpms/R-repurrrsive.git /var/lib/mock/f45-build-6356-348/root/chroot_tmpdir/scmroot/R-repurrrsive
Cloning into '/var/lib/mock/f45-build-6356-348/root/chroot_tmpdir/scmroot/R-repurrrsive'...
$ git fetch origin 336f72a900310338c699fc33662af2207fa6f6d4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-repurrrsive
 * [new ref]         336f72a900310338c699fc33662af2207fa6f6d4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 336f72a Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild