$ git clone -n https://src.fedoraproject.org/rpms/R-readxl.git /var/lib/mock/f38-build-side-42-init-devel-933556-28750/root/chroot_tmpdir/scmroot/R-readxl
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-933556-28750/root/chroot_tmpdir/scmroot/R-readxl'...
$ git fetch origin f0499ee028720a6051eeb0e81ae06918ea7439aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-readxl
 * [new ref]         f0499ee028720a6051eeb0e81ae06918ea7439aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f0499ee BR: R-covr