$ git clone -n https://src.fedoraproject.org/rpms/R-winch.git /var/lib/mock/f45-build-6511-349/root/chroot_tmpdir/scmroot/R-winch
Cloning into '/var/lib/mock/f45-build-6511-349/root/chroot_tmpdir/scmroot/R-winch'...
$ git fetch origin ac628ab0f2732b70d1328980166d4ce961269e8e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-winch
 * [new ref]         ac628ab0f2732b70d1328980166d4ce961269e8e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ac628ab Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild