$ git clone -n https://src.fedoraproject.org/rpms/R-testthat.git /var/lib/mock/f40-build-1930469-25111/root/chroot_tmpdir/scmroot/R-testthat
Cloning into '/var/lib/mock/f40-build-1930469-25111/root/chroot_tmpdir/scmroot/R-testthat'...
$ git fetch origin 985438bc5f66f59b41185b47402855238230e15d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-testthat
 * [new ref]         985438bc5f66f59b41185b47402855238230e15d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 985438b R-maint-sig mass rebuild