$ git clone -n https://src.fedoraproject.org/rpms/R-devtools /var/lib/mock/f41-build-side-1-3149578-40459/root/chroot_tmpdir/scmroot/R-devtools
Cloning into '/var/lib/mock/f41-build-side-1-3149578-40459/root/chroot_tmpdir/scmroot/R-devtools'...
$ git fetch origin a7696fbcb6d6ab008d3f1f01f8dea4ffdfde71d5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-devtools
 * [new ref]         a7696fbcb6d6ab008d3f1f01f8dea4ffdfde71d5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a7696fb convert GPLv2+ license to SPDX