$ git clone -n https://src.fedoraproject.org/rpms/R-gee.git /var/lib/mock/f38-build-723940-99307/root/chroot_tmpdir/scmroot/R-gee
Cloning into '/var/lib/mock/f38-build-723940-99307/root/chroot_tmpdir/scmroot/R-gee'...
$ git fetch origin 28a531bd33a9dcbd28ced20fc723209b489c838a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-gee
 * [new ref]         28a531bd33a9dcbd28ced20fc723209b489c838a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 28a531b R-maint-sig mass rebuild