$ git clone -n https://src.fedoraproject.org/rpms/R-fastmap.git /var/lib/mock/f38-build-side-42-init-devel-978064-28984/root/chroot_tmpdir/scmroot/R-fastmap
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-978064-28984/root/chroot_tmpdir/scmroot/R-fastmap'...
$ git fetch origin f1112982fad88b0a2f13adacfde989a0feaa59aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-fastmap
 * [new ref]         f1112982fad88b0a2f13adacfde989a0feaa59aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f111298 new sources