$ git clone -n https://src.fedoraproject.org/rpms/R-dplyr.git /var/lib/mock/f43-build-58895040-6569073/root/chroot_tmpdir/scmroot/R-dplyr
Cloning into '/var/lib/mock/f43-build-58895040-6569073/root/chroot_tmpdir/scmroot/R-dplyr'...
$ git fetch origin efa9e13b0bd7791eaf67b0b77113d9d542c28d9c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-dplyr
 * [new ref]         efa9e13b0bd7791eaf67b0b77113d9d542c28d9c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at efa9e13 R-maint-sig mass rebuild