$ git clone -n https://src.fedoraproject.org/rpms/R-lubridate.git /var/lib/mock/f41-build-side-110418-58949899-6569392/root/chroot_tmpdir/scmroot/R-lubridate
Cloning into '/var/lib/mock/f41-build-side-110418-58949899-6569392/root/chroot_tmpdir/scmroot/R-lubridate'...
$ git fetch origin 04b1d565ec44e39ec344006f20c7faccb034e666:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lubridate
 * [new ref]         04b1d565ec44e39ec344006f20c7faccb034e666 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 04b1d56 Add missing file